Place a few spoonfuls of enchilada sauce in the bottom of a 9x9 inch glass baking dish to prevent sticking.
Place 2 tortillas in the bottom of the dish, overlapping slightly to cover the entire surface.
Layer the beans, chicken, about 1/2 cup cheese, and about 3/4 cup enchilada sauce. Repeat once to make a total of 2 layers.
Cover the top with the remaining enchilada sauce and 1 cup of cheese. Cover the baking dish tightly with well-oiled aluminum foil and bake for about 30 minutes.
Remove the foil and bake uncovered for an additional 5 minutes or until the cheese is starting to brown and the sauce is bubbling.
Allow the casserole to rest for at least 15 minutes before cutting and serving. Top with desired toppings like cilantro or sour cream.
Notes
This recipe is easily adaptable. For a gluten-free version, use corn tortillas. You can add extra vegetables like sautéed bell peppers or spinach between the layers.