Creating the Chicken Enchilada Rice Casserole is effortless if you follow these clear steps:

1. Preheat the Oven: Set your oven to 350°F (175°C).
2. Sauté Onions: In a skillet, heat olive oil over medium heat. Add diced onions and sauté until they are translucent, about 5 minutes.
3. Mix Ingredients: In a large bowl, combine the cooked rice, shredded chicken, enchilada sauce, black beans, corn, half of the cheese, sautéed onions, and taco seasoning. Stir until well combined.
4. Season: Taste the mixture and season with salt and pepper as needed.
5. Transfer to Baking Dish: Pour the mixture into a greased 9×13-inch baking dish. Spread it evenly.
6. Add Remaining Cheese: Sprinkle the remaining cheese evenly over the top of the casserole.
7. Bake in Oven: Cover the dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for an additional 15-20 minutes, or until the cheese is melted and bubbly.
8. Cool: Once baked, let the casserole cool for about 5-10 minutes before serving. This will help it set up nicely.
9. Serve: Garnish with optional toppings, if desired, before serving.

These simple steps will guide you in preparing this incredible casserole that will surely become a household favorite.