Preheat oven to 350°F.
Combine enchilada sauce, chicken broth, sour cream, undrained green chiles, and taco seasoning in a large bowl and mix until well blended.
Stir in cooked chicken, black beans, cooked rice, corn, and diced red bell pepper until combined, then set the mixture aside.
Place two flour tortillas in a 9x13-inch baking dish, cutting them to fit if preferred.
Spread half of the chicken mixture over the tortillas.
Top with half of the cheddar and Monterey Jack cheeses.
Repeat the layering process once more with the remaining tortillas, chicken mixture, and cheeses.
Cover and bake on the middle rack for approximately 20 minutes until the cheese is melted and the casserole is heated through.
Garnish with chopped cilantro if desired and serve.