01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish.
02 - In a large skillet over medium heat, sauté diced onion in a little oil for 3–4 minutes until softened.
03 - Add shredded chicken, black beans, corn, cumin, chili powder, garlic powder, salt, and pepper. Stir well and cook for 2–3 minutes to combine flavors. Remove from heat.
04 - Spread 1/2 cup enchilada sauce on the bottom of the prepared baking dish.
05 - Layer 4 tortillas over the sauce, tearing as needed to cover the bottom.
06 - Spread half the chicken mixture over the tortillas. Top with 1/2 cup enchilada sauce and 2/3 cup shredded cheese.
07 - Repeat with 4 more tortillas, the remaining chicken mixture, 1/2 cup enchilada sauce, and another 2/3 cup cheese.
08 - Top with the final 4 tortillas, remaining enchilada sauce, and the rest of the cheese.
09 - Cover with foil and bake for 20 minutes. Remove foil and bake an additional 10–15 minutes, until cheese is bubbling and lightly golden.
10 - Let rest 10 minutes before slicing. Garnish with cilantro, sour cream, avocado, and lime if desired.