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Sweet Potato Pumpkin Casserole with Pecans and Marshmallows

If you’re looking for the perfect sweet and cozy side dish for Thanksgiving, Christmas, or any fall family gathering, this Sweet Potato Pumpkin Casserole is a must-make! Made with creamy mashed sweet potatoes, rich pumpkin puree, brown sugar, warm cinnamon, and a touch of vanilla, this comforting casserole is topped with crunchy pecans and fluffy mini marshmallows that turn beautifully golden in the oven.

Every bite brings together the natural sweetness of sweet potatoes, the earthy flavor of pumpkin, a buttery filling, and a delicious contrast of crunchy nuts and soft, toasted marshmallows. It’s part classic sweet potato casserole, part pumpkin dessert, and completely irresistible.

The best part? This recipe uses simple ingredients and comes together with minimal effort. Just mash, mix, add the toppings, and bake until everything is warm, bubbly, and golden.

Whether you’re planning a holiday feast or simply craving a cozy fall-inspired dish, this Sweet Potato Pumpkin Casserole deserves a spot on your table!

Why You’ll Love This Sweet Potato Pumpkin Casserole

Perfect for the holidays: A beautiful addition to Thanksgiving, Christmas, and autumn dinner menus.
Creamy and flavorful: Mashed sweet potatoes and pumpkin create a smooth, rich filling.
Sweet and crunchy topping: Pecans add nutty crunch while mini marshmallows become soft, puffy, and golden.
Easy to prepare: The sweet potatoes can be cooked ahead of time, making assembly quick and simple.
Made with familiar ingredients: Everything is easy to find at most grocery stores.
A versatile side dish: Serve it alongside roasted turkey, baked ham, roast chicken, or other holiday favorites.
Dessert-like comfort food: It’s sweet enough to feel special but works beautifully as part of a savory meal.

Recipe at a Glance

Prep time: 20 minutes
Cook time: 20–25 minutes
Resting time: 5 minutes
Total time: Approximately 45–50 minutes, excluding extra time needed to cook and cool the sweet potatoes
Servings: 8–10
Course: Side Dish
Cuisine: American
Cooking method: Baking
Difficulty: Easy

Ingredients You’ll Need

For the Sweet Potato Pumpkin Filling

3 large sweet potatoes, cooked and mashed

Sweet potatoes create the hearty, naturally sweet base of the casserole. Choose sweet potatoes that feel firm and have smooth skin. Once cooked and mashed, they should be tender and easy to blend.

1 cup pumpkin puree

Pumpkin adds a rich autumn flavor and a smooth texture. Use plain canned pumpkin puree, not pumpkin pie filling, which already contains sweeteners and spices.

½ cup brown sugar

Brown sugar adds sweetness and a hint of molasses flavor that complements the pumpkin and sweet potatoes. Light or dark brown sugar both work well.

½ cup sour cream

Sour cream adds creaminess and a subtle tang that balances the sweetness. Full-fat sour cream gives the richest result.

4 tablespoons butter, melted

Butter makes the filling rich, smooth, and flavorful. Unsalted butter gives you better control over the seasoning.

1 teaspoon ground cinnamon

Cinnamon adds the warm, cozy flavor that makes this casserole perfect for fall and winter meals.

1 teaspoon vanilla extract

Vanilla enhances the sweetness and rounds out the flavors of the pumpkin and sweet potatoes.

For the Topping

1 cup chopped pecans

Pecans add a buttery, nutty crunch that contrasts beautifully with the soft filling and marshmallows. Chop them into small pieces so they distribute evenly.

2 cups mini marshmallows

Mini marshmallows create the signature sweet topping. They puff up in the oven and become lightly golden, adding a soft, toasted finish.

How to Make Sweet Potato Pumpkin Casserole

Step 1: Prepare the Oven and Baking Dish

Preheat your oven to 375°F (190°C).

Lightly grease a medium baking dish, approximately 2-quart size, with butter or nonstick cooking spray. A dish around 8 × 11 inches or 9 × 9 inches will generally work, depending on its depth.

Set the prepared dish aside while you make the filling.

Step 2: Cook and Mash the Sweet Potatoes

Peel the sweet potatoes and cut them into evenly sized chunks. Place them in a pot of water, bring to a boil, and simmer until they are fork-tender, usually about 15–20 minutes depending on their size.

Drain thoroughly and allow excess steam to escape for a minute or two. This helps prevent a watery casserole.

Mash the sweet potatoes with a potato masher until mostly smooth. A few small lumps are fine if you prefer a more rustic texture.

For a richer flavor, you can also bake the sweet potatoes whole until tender, then scoop out the flesh and mash it.

Step 3: Mix the Creamy Filling

In a large mixing bowl, combine the mashed sweet potatoes and pumpkin puree.

Add the brown sugar, sour cream, melted butter, cinnamon, and vanilla extract.

Stir until everything is evenly incorporated and the mixture looks creamy and smooth. Taste a small spoonful and adjust the sweetness or cinnamon if desired.

If the mixture seems very loose, make sure the sweet potatoes were well drained before mashing. Excess moisture can affect the final texture.

Step 4: Transfer the Filling to the Baking Dish

Spoon the sweet potato pumpkin mixture into the prepared baking dish.

Spread it evenly with a spatula, smoothing the top so the casserole bakes consistently.

Step 5: Add the Pecans and Marshmallows

Sprinkle the chopped pecans evenly over the filling.

Cover the surface with mini marshmallows, distributing them so most of the casserole is topped with a fluffy layer.

For extra crunch, reserve a small handful of pecans to sprinkle over the finished casserole just before serving.

Step 6: Bake Until Golden

Place the casserole in the preheated oven and bake for 20–25 minutes, until the filling is hot and the marshmallows are puffed and lightly golden.

Keep an eye on the topping during the final few minutes because marshmallows can brown quickly. If they begin to darken too much before the filling is heated through, loosely cover the dish with foil.

If the filling was refrigerated before baking, allow extra time and check that the center is thoroughly hot before serving.

Step 7: Rest and Serve

Remove the casserole from the oven and let it rest for about 5 minutes.

This brief resting time allows the filling to settle slightly and makes serving easier.

Spoon into bowls or onto plates and serve warm alongside your favorite holiday dishes.

Tips for the Best Sweet Potato Pumpkin Casserole

Drain the sweet potatoes well: Too much moisture can make the filling loose.
Use plain pumpkin puree: Pumpkin pie filling contains added sugar and spices that can change the recipe.
Mash while the potatoes are warm: Warm sweet potatoes are easier to mash smoothly.
Don’t overmix: Mix just until the ingredients are evenly combined.
Taste before baking: Adjust the cinnamon or brown sugar to suit your preference.
Chop the pecans evenly: Smaller pieces distribute more consistently across the topping.
Add marshmallows near the end if needed: If you prefer a less toasted topping, bake the filling and pecans first, then add marshmallows for the final 10–15 minutes.
Watch the oven closely: Marshmallows can go from golden to burnt quickly.
Let the casserole rest: Five minutes makes it easier to serve neatly.
Use a shallow baking dish: A relatively even layer helps the filling heat consistently.

Variations and Substitutions

1. Sweet Potato Pumpkin Casserole with Streusel

For a crunchy, bakery-style topping, combine ½ cup flour, ⅓ cup brown sugar, 3 tablespoons softened butter, and ½ teaspoon cinnamon until crumbly. Sprinkle it over the filling with the pecans. Bake until the topping is golden and the filling is hot, adding the marshmallows near the end if desired.

2. Maple Sweet Potato Pumpkin Casserole

Replace part of the brown sugar with 2–3 tablespoons of pure maple syrup. Maple adds a lovely flavor that pairs especially well with pecans.

Because maple syrup adds moisture, avoid adding too much if your sweet potatoes are already soft.

3. Brown Butter Version

For a deeper, nuttier flavor, gently cook the butter in a saucepan until the milk solids turn golden and smell nutty. Let it cool slightly before stirring it into the filling.

4. Add Warm Fall Spices

Along with the cinnamon, add ¼ teaspoon ground nutmeg, a pinch of ground ginger, or a small pinch of ground cloves. Start with modest amounts so the spices don’t overpower the pumpkin.

5. Sweet Potato Pumpkin Casserole with Walnuts

Replace the pecans with chopped walnuts for a slightly earthier, pleasantly crunchy topping.

6. Coconut-Pecan Topping

Add ½ cup shredded coconut to the chopped pecans for extra texture and a subtle tropical note.

7. Less-Sweet Casserole

Reduce the brown sugar to ¼ cup, especially if your sweet potatoes are naturally very sweet. You can also reduce the marshmallows or use them only as a light topping.

8. Dairy-Free Version

Use a plant-based butter alternative and an unsweetened dairy-free sour cream alternative. Check the marshmallow ingredients as well, since formulations vary.

9. Nut-Free Version

Omit the pecans and use a crunchy topping made from toasted pumpkin seeds, provided they meet your dietary needs. You can also simply make the casserole with marshmallows alone.

10. Add a Little Orange

Stir 1 teaspoon of finely grated orange zest into the filling. The citrus brightens the sweetness and pairs wonderfully with pumpkin and cinnamon.

What to Serve with Sweet Potato Pumpkin Casserole

This casserole is especially popular during holiday meals, where its sweet flavor complements savory main dishes.

Roasted turkey: A classic Thanksgiving pairing.
Baked ham: The sweet and salty flavors work beautifully together.
Roast chicken: An easy choice for a family dinner.
Roasted pork loin: The pumpkin, cinnamon, and pecans complement the savory pork.
Green bean casserole: Adds another traditional holiday favorite to the table.
Roasted Brussels sprouts: Their savory, slightly bitter flavor balances the sweetness.
Garlic mashed potatoes: A comforting option for a generous holiday spread.
Stuffing or dressing: Complements the casserole’s sweet, soft texture.
Cranberry sauce: Its tartness cuts through the richness and sweetness.

For a smaller meal, serve it with roasted chicken and green vegetables. For a holiday feast, add it to your Thanksgiving or Christmas side-dish lineup.

Make-Ahead Instructions

This casserole is easy to prepare ahead, which makes it especially useful when you’re cooking a large holiday meal.

Cook and mash the sweet potatoes.
Mix the sweet potatoes with the pumpkin, brown sugar, sour cream, butter, cinnamon, and vanilla.
Transfer the filling to the greased baking dish.
Cover and refrigerate the filling for up to 24 hours.
When ready to bake, add the pecans and marshmallows.
Bake at 375°F (190°C) until the center is hot and the topping is puffed and golden.

If the filling is cold from the refrigerator, it will take longer than 20–25 minutes to heat through. Check the center rather than relying only on the original baking time. For more even heating, let the dish sit at room temperature briefly while the oven preheats, but don’t leave it out for more than two hours.

For the best marshmallow texture, add the topping shortly before baking rather than refrigerating the assembled casserole for an extended period.

How to Store Leftovers

Let the casserole cool slightly, then refrigerate leftovers in an airtight container or cover the baking dish securely. Refrigerate within two hours of cooking.

Store in the refrigerator for 3–4 days.

The marshmallows will soften during storage, but the filling will remain delicious. If you want to refresh the topping, add a few fresh mini marshmallows before reheating.

How to Reheat Sweet Potato Pumpkin Casserole

In the Oven

Preheat the oven to 325°F (165°C). Place the desired portion in an oven-safe dish and cover loosely with foil to prevent the marshmallows from browning too quickly.

Heat until the center is hot, removing the foil during the final few minutes if you want to refresh the topping.

In the Microwave

Place an individual serving in a microwave-safe bowl or plate. Heat in 30-second intervals until hot, checking between intervals.

The marshmallows may become sticky or lose their toasted texture, but the casserole will still taste wonderful.

For a Freshly Toasted Topping

Reheat the filling until hot, then add a few fresh mini marshmallows and briefly place the dish under the broiler, watching continuously. Marshmallows brown very quickly, so don’t leave them unattended.

Can You Freeze Sweet Potato Pumpkin Casserole?

Yes, the sweet potato and pumpkin filling freezes reasonably well, although the sour cream may slightly change the texture after thawing.

For the best results, prepare the filling without the pecans and marshmallows, transfer it to a freezer-safe container, and freeze for up to 2 months for best quality.

Thaw overnight in the refrigerator, transfer to a baking dish if needed, add the toppings, and bake until thoroughly hot.

You can freeze the fully assembled casserole, but the marshmallows may become sticky or lose their original texture. Adding fresh marshmallows just before baking produces a better finish.

Frequently Asked Questions

1. Can I use canned sweet potatoes?

Yes. Use canned sweet potatoes that are plain rather than packed in syrup. Drain them thoroughly and mash them before measuring or mixing. Since canned sweet potatoes are often softer and sweeter, you may need less brown sugar.

2. Can I use canned pumpkin puree?

Absolutely. Plain canned pumpkin puree is convenient and works very well in this recipe. Avoid pumpkin pie filling, which already contains sweeteners and spices.

3. Can I make this casserole the day before Thanksgiving?

Yes. Prepare the filling, spread it in the baking dish, cover, and refrigerate for up to 24 hours. Add the pecans and marshmallows shortly before baking.

4. Do I have to peel the sweet potatoes?

For this recipe, peeling is recommended because it creates a smoother filling. If you bake the sweet potatoes whole, scoop out the flesh after cooking and discard the skins.

5. Can I bake the sweet potatoes instead of boiling them?

Yes. Baking whole sweet potatoes until tender can produce a deeper, sweeter flavor. Let them cool enough to handle, scoop out the flesh, and mash it before mixing.

6. Why is my casserole watery?

The sweet potatoes may have retained too much cooking water, or the pumpkin puree may be particularly moist. Drain boiled potatoes well and let excess steam escape before mashing.

7. Can I make this casserole without sour cream?

Yes. Plain Greek yogurt can work as a substitute, although it may add a slightly tangier flavor. A suitable dairy-free sour cream alternative also works.

8. Can I use salted butter?

Yes. If you use salted butter, taste the filling before adding any extra salt.

9. Can I replace brown sugar with white sugar?

Yes, but brown sugar contributes a mild molasses flavor that complements the pumpkin. White sugar will sweeten the filling without that same depth.

10. Can I use maple syrup instead of brown sugar?

Yes. Replace some of the brown sugar with pure maple syrup. Avoid using too much liquid sweetener, as it can make the filling softer.

11. Can I leave out the marshmallows?

Of course. The casserole is delicious with just pecans, or you can add a streusel topping for crunch.

12. Can I use marshmallow fluff instead of mini marshmallows?

You can, but marshmallow fluff behaves differently and may spread or brown unevenly. Mini marshmallows are the easiest choice for the classic toasted topping.

13. How do I keep the marshmallows from burning?

Watch the casserole during the final few minutes. If necessary, bake the filling and pecans first and add the marshmallows during the last 10–15 minutes.

14. Can I make this casserole less sweet?

Yes. Reduce the brown sugar to ¼ cup and use fewer marshmallows. Sweet potatoes naturally contain sweetness, so the casserole will still have plenty of flavor.

15. Can I make it without nuts?

Yes. Simply omit the pecans or replace them with a suitable nut-free crunchy topping.

16. What size baking dish should I use?

A greased 2-quart baking dish is a good starting point. An 8 × 11-inch or 9 × 9-inch dish usually works, depending on its depth and the exact volume of your filling.

17. How do I know when the casserole is ready?

The filling should be hot throughout, and the marshmallows should be puffed and lightly golden. If the filling was refrigerated, allow additional baking time.

18. How long do leftovers last?

Store leftovers in an airtight container in the refrigerator for 3–4 days. Refrigerate within two hours of cooking.

19. Can I freeze the casserole?

Yes. For the best texture, freeze the filling without the marshmallows and pecans for up to about 2 months. Thaw in the refrigerator, add the toppings, and bake until hot.

20. Is this a side dish or a dessert?

It can be either! Its sweetness and marshmallow topping make it dessert-like, but it is traditionally served as a holiday side dish alongside savory foods.

20 Tips and Secrets for the Perfect Casserole

Choose similar-sized sweet potatoes: They cook more evenly when cut into uniform chunks.
Drain thoroughly after boiling: Excess water is one of the main causes of a loose filling.
Mash while warm: Warm sweet potatoes are easier to mash and blend.
Use plain pumpkin puree: This gives you control over the sweetness and spices.
Measure the pumpkin accurately: Too much can make the casserole softer than intended.
Use softened sour cream: It blends more easily into the warm sweet potatoes.
Let melted butter cool slightly: This makes it easier to mix without overheating the other ingredients.
Mix until just combined: Overworking the filling isn’t necessary.
Taste before adding toppings: Adjust the brown sugar and cinnamon to your preference.
Use fresh cinnamon: Fresh, aromatic spices make the flavor more noticeable.
Chop pecans into small pieces: They distribute more evenly and are easier to eat.
Spread the filling evenly: A level surface helps the casserole heat consistently.
Keep marshmallows away from the dish edges: This can help reduce sticking and excessive browning.
Add marshmallows later if preferred: This gives you more control over how toasted they become.
Watch the final minutes carefully: Marshmallows can brown rapidly.
Use foil strategically: A loose foil cover can protect the topping if it browns too soon.
Prepare the filling ahead: This saves valuable oven and preparation time on holidays.
Add toppings shortly before baking: Pecans stay crunchier and marshmallows keep their shape better.
Let it rest before serving: A short rest makes portions easier to scoop.
Refresh leftovers with fresh marshmallows: Add them before reheating in the oven for a more appealing topping.

When to Serve Sweet Potato Pumpkin Casserole

This recipe is especially suited to occasions when you want a warm, colorful, seasonal side dish.

Thanksgiving dinner: A sweet and creamy addition to turkey, stuffing, and cranberry sauce.
Christmas dinner: A festive dish with warm spices and a golden marshmallow topping.
Fall potlucks: Easy to transport when covered securely and kept at a safe temperature.
Sunday family dinners: A comforting accompaniment to roast chicken or pork.
Friendsgiving gatherings: A crowd-pleasing dish that can be prepared in advance.
Holiday buffets: Its bright orange filling and toasted topping look beautiful on the table.

Final Thoughts

This Sweet Potato Pumpkin Casserole combines everything we love about fall comfort food: creamy sweet potatoes, rich pumpkin, brown sugar, warm cinnamon, buttery pecans, and fluffy golden marshmallows.

It’s simple enough for a family dinner but special enough for Thanksgiving or Christmas. Preparing the filling ahead makes it even easier to fit into a busy holiday cooking schedule, while the pecan-and-marshmallow topping gives it that classic festive finish.

Serve it warm alongside your favorite savory dishes, and don’t be surprised if everyone comes back for seconds. This cozy casserole is a delicious way to bring a little extra sweetness to the holiday table!