Preheat your oven to 350°F (175°C).
Prepare the bell peppers by cutting the tops off and removing the seeds and membranes. Place them upright in a baking dish.
In a mixing bowl, combine the black beans, corn, diced tomatoes, ground cumin, chili powder, garlic powder, salt, and pepper. Mix well until all the ingredients are evenly incorporated.
Spoon the bean mixture into each bell pepper, packing it down lightly to ensure they're filled.
Top each stuffed pepper with shredded cheese, distributing it evenly among them.
Cover the baking dish with aluminum foil to prevent the peppers from drying out during cooking.
Bake in the preheated oven for 20 minutes. After 20 minutes, remove the foil and bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let cool for a few minutes before serving. Garnish with chopped cilantro and serve with sour cream or Greek yogurt if desired.