Preheat the Oven:
Preheat your oven to 400°F (200°C). Lightly spray a casserole dish with cooking spray and set aside.
Season the Chicken:
Lay the chicken breasts on a cutting board and season with salt and black pepper. Sprinkle ½ tbsp of taco seasoning over the chicken breasts, then flip them over and season the other side with the remaining taco seasoning. Set aside.
Prepare the Rice & Bean Layer:
In the greased casserole dish, combine the cooked rice, black beans, corn kernels, garlic powder, 1 ½ cups of salsa, ½ tsp salt, and a pinch of black pepper. Stir everything together until well-mixed, then spread the mixture out evenly across the bottom of the dish.
Assemble the Casserole:
Place the seasoned chicken breasts on top of the rice mixture. Pour the remaining ½ cup of salsa over the chicken.
Bake the Casserole:
Bake the casserole uncovered for 30-35 minutes, or until the chicken is cooked through (the internal temperature should reach 158°F). Cooking time may vary based on the thickness of the chicken breasts.
Add Cheese & Finish Baking:
Remove the casserole from the oven and sprinkle the shredded cheddar cheese over the chicken. Return the casserole to the oven and bake for an additional 4-5 minutes, or until the cheese has melted.
Serve:
Once the cheese has melted, remove the casserole from the oven. Divide the chicken and rice mixture into portions and serve warm with your favorite toppings, such as sour cream, avocado, or chopped cilantro.