Preheat the oven to 375 degrees F / 190 degrees C.
Grease a casserole dish with cooking spray and set it aside.
In a large bowl, combine the shredded chicken, black beans, diced bell pepper, corn, sour cream, salsa, diced green chilies and taco seasoning. Mix all the ingredients until well combined.
Transfer half of the chicken mixture to the prepared casserole dish and spread it out evenly.
Layer 1 cup of crushed tortilla chips over the chicken mixture.
Spread the remaining chicken mixture over the tortilla chips then top with the remaining chips.
Generously sprinkle a mixture of Colby Jack cheese and Monterey Jack cheese over the casserole, ensuring it covers the top evenly.
Bake the casserole in the preheated oven for 30 minutes, or until the cheese is melted and bubbly.
Once done, remove the casserole from the oven and let it rest for 10 minutes.
Finally, top the casserole with diced tomatoes, diced avocado, sliced jalapenos, and chopped cilantro.
Serve the chicken taco casserole while it is still warm and enjoy!