Add the chopped spinach and corn to the pan with the beef. Cook, stirring frequently, until the spinach is wilted and the mixture is thoroughly combined.
Spoon the beef and spinach mixture into the hollowed-out tomatoes, distributing it evenly among them. If there is any leftover beef mixture, you can spread it in the bottom of the baking dish around the tomatoes.
If desired, sprinkle shredded sharp cheddar cheese over the stuffed tomatoes.
Bake in the preheated oven for about 15 minutes, or until the cheese is melted and bubbly, and the tomatoes are heated through.
Once out of the oven, garnish the stuffed tomatoes with freshly chopped cilantro.
Serve hot as a delicious and flavorful main dish or as a side. Enjoy your stuffed taco tomatoes!