In a large skillet, heat the olive oil over medium heat. Add the diced chicken and season with salt, pepper, cumin, chili powder, and smoked paprika. Cook for about 5-7 minutes, or until the chicken is no longer pink.
Add the sliced onion, red and yellow bell peppers, and garlic to the skillet. Sauté for another 5-6 minutes, until the vegetables are tender.
In a large mixing bowl, combine the black beans, corn, salsa, and cooked brown rice or quinoa. Stir in the cooked chicken and vegetable mixture.
Transfer the entire mixture into a greased 9x13 inch baking dish. Spread it evenly across the dish.
Top with shredded cheddar cheese, covering the entire casserole.
Bake in the preheated oven for about 20-25 minutes, or until the cheese is bubbly and golden brown.
Once baked, remove from the oven and let it sit for a few minutes. Garnish with fresh cilantro and sliced jalapeños if desired.
Notes
Garnish with fresh cilantro and jalapeños for added flavor.