Preheat oven to 350° F.
Heat 2 Tablespoons of oil in a large skillet over medium heat. Add the chopped pepper and onion and sauté for 5-6 minutes, until tender.
Add the shredded chicken, black beans, green chilies and all but 1 cup of the enchilada sauce to the skillet with the sauteéd veggies. Cook, stirring occasionally, until warmed through.
Pour the reserved 1 cup of sauce into a 9x13 inch pan. Layer 6 tortillas over the sauce. Top with 1/3 of the chicken mixture and 1/3 of the cheese. Repeat the layers twice more.
Bake, uncovered, at 350° for 30 minutes.
Remove from oven and garnish with cilantro, sour cream, jalapeños, avocado, or any toppings of your choice.