Preheat Oven: Set oven to 375°F (190°C).
Prepare Chicken: Pat chicken dry. Drizzle with melted butter or olive oil. In a small bowl, mix chili powder, cumin, garlic powder, onion powder, smoked paprika, oregano, salt, and pepper. Rub the spice mixture evenly over both sides of the chicken breasts.
Assemble Base Layer: In a 9x13-inch baking dish, combine black beans, corn, fire-roasted tomatoes (if using), cooked rice, green chiles, and 1 cup of salsa. Stir until well mixed. Season with salt and pepper to taste, then spread the mixture evenly in the dish.
Add Chicken and Salsa: Place the seasoned chicken breasts on top of the rice mixture. Spoon the remaining ½ cup of salsa over the chicken.
Bake: Cover the dish with foil and bake for 30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).
Add Cheese: Remove the foil and sprinkle shredded cheese over the chicken. Return to the oven and bake, uncovered, for an additional 5 minutes, or until the cheese is melted and bubbly.
Serve: Garnish with sour cream, chopped cilantro, diced avocado, sliced jalapeños, and lime wedges as desired. Serve hot.