French Onion Soup Burgers 
Ingredients:
1 lb ground beef
2 large onions, thinly sliced
2 tablespoons butter
1 teaspoon sugar
1/2 cup beef broth
2 tablespoons Worcestershire sauce
1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried thyme)
Salt and pepper to taste
4 slices of Gruyère or Swiss cheese
4 hamburger buns
1 clove garlic, minced (optional for garlic butter buns)
Additional butter for buns
Directions:
Caramelize the Onions:
In a large skillet, melt the butter over medium heat. Add the thinly sliced onions and cook, stirring occasionally, until they begin to soften, about 5 minutes.
Sprinkle the onions with sugar and continue to cook, stirring frequently, until they are golden brown and caramelized, about 15-20 minutes.
Add the beef broth, Worcestershire sauce, and thyme to the onions. Stir to combine and cook for an additional 5 minutes, or until the liquid is mostly absorbed. Season with salt and pepper to taste. Remove from heat and set aside.
Prepare the Burgers:
In a medium bowl, season the ground beef with salt and pepper. Divide the beef into 4 equal portions and shape them into patties.
Preheat a grill or skillet over medium-high heat. Cook the patties for 3-4 minutes per side, or until they reach your desired level of doneness.
Prepare the Buns:
If using garlic butter, melt additional butter in a small skillet and add the minced garlic. Cook for 1-2 minutes until fragrant.
Brush the hamburger buns with the garlic butter (or plain melted butter) and toast them on the grill or in a skillet until golden brown.
Assemble the Burgers:
Place a cooked patty on the bottom half of each bun. Top each patty with a generous portion of the caramelized onion mixture.
Place a slice of Gruyère or Swiss cheese on top of the onions. Place the assembled burgers back on the grill or in a skillet and cover for 1-2 minutes, or until the cheese is melted.
Top with the other half of the bun.
