Start by preheating your oven to 350°F (175°C). Grease a 9x13 inch baking dish with cooking spray or a small amount of olive oil to prevent sticking.
In a large skillet set over medium heat, add the ground beef. Cook until it is browned and no longer pink, breaking it apart with a spatula as it cooks. Once browned, drain the excess fat from the pan.
To the skillet, add the finely diced onion, minced garlic, and diced bell pepper. Sauté for about 5-7 minutes, or until the onion becomes translucent and the bell pepper is tender.
Combine the corn, rinsed black beans, and the entire can of diced tomatoes (including their juices) into the skillet. Sprinkle in the chili powder, ground cumin, and season with salt and pepper to your taste. Stir everything together and let it simmer for 5 minutes to meld the flavors.
Once simmered, fold in the cooked rice, stirring until the mixture is well combined and evenly distributed.
Carefully transfer this hearty mixture into the greased baking dish, spreading it out evenly to ensure it cooks thoroughly.
Generously sprinkle the shredded sharp cheddar cheese evenly over the top of the casserole for a gooey, cheesy finish.
Place the baking dish in the preheated oven and bake for 20-25 minutes, or until the cheese is melted, bubbly, and slightly golden brown on top.
Remove from the oven and allow the casserole to cool for a few minutes to set. Before serving, garnish with freshly chopped cilantro for a pop of color and flavor.
Notes
Serve directly from the baking dish with a lime wedge for added zest.