Preheat the Oven: Start by preheating the oven to 350°F (175°C).
Cook the Ground Beef: Cook the ground beef in a skillet over medium heat until browned. Add diced onions and bell peppers, cooking until vegetables are softened.
Combine Ingredients: In a large mixing bowl, combine the cooked beef mixture, canned chili, black beans, chili powder, salt, and pepper.
Layer the Casserole: In a greased baking dish, create layers by starting with half of the Fritos at the bottom. Add the beef mixture on top, followed by a layer of shredded cheddar cheese. Repeat the layers, finishing with a final layer of cheese.
Bake: Place the baking dish in the preheated oven and bake for 20-25 minutes or until the cheese is melted and bubbly.
Serve: Once out of the oven, let it cool slightly. Serve with dollops of sour cream, additional Fritos for crunch, and garnish with fresh cilantro if desired.