Creating the Fiesta Chicken Bake is as easy as following these steps:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Prepare the Chicken: In a large skillet, heat the olive oil over medium heat. Add the cubed chicken and season with salt and pepper. Cook for about 5-7 minutes until the chicken is golden brown.
3. Add the Sauce: Stir in the taco seasoning, diced tomatoes with green chilies, black beans, corn, red bell pepper, and green bell pepper. Mix thoroughly and allow it to simmer for about 5 minutes.
4. Combine Ingredients: Transfer the chicken and vegetable mixture to a 9×13 inch baking dish and spread evenly.
5. Top with Cheese: Sprinkle the shredded Monterey Jack cheese over the chicken mixture. Follow with an even layer of cheddar cheese on top.
6. Bake: Put the baking dish in the preheated oven and bake for 25-30 minutes or until the cheese is bubbly and golden.
7. Garnish: Once baked, remove from the oven and sprinkle chopped green onions and fresh cilantro on top for added flavor.
8. Serve: Let the dish sit for a few minutes before serving to allow the cheese to set.

This straightforward guide will have you creating an incredible Fiesta Chicken Bake in no time, charming your family and satisfying your guests!