In a large skillet, heat olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until the onion is translucent, about 3-4 minutes.

Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 5-7 minutes. Drain excess fat if necessary.

Stir in the diced tomatoes, kidney beans, corn, bell peppers, chili powder, cumin, salt, and black pepper. Bring the mixture to a simmer and cook for 10 minutes, allowing the flavors to meld.

Preheat your oven to 350°F. In a large casserole dish, combine the cooked rice with the beef mixture. Stir well to combine.

Top the casserole with shredded cheddar cheese. Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.

Let the casserole cool for a few minutes before serving.