01 - Preheat oven to 375°F. Lightly grease a 9x13 inch baking dish with cooking spray or oil.
02 - In a large bowl, mix shredded chicken, 1 cup enchilada sauce, black beans, corn, red onion, cumin, chili powder, garlic powder, salt, and pepper until thoroughly combined.
03 - Spread 1/2 cup enchilada sauce evenly across the bottom of the prepared baking dish.
04 - Arrange four tortillas over the sauce, tearing as necessary to cover the bottom completely.
05 - Distribute half the chicken mixture over the tortillas. Sprinkle with 2/3 cup shredded cheese.
06 - Add another layer of tortillas. Top with remaining chicken mixture and another 2/3 cup cheese.
07 - Place remaining tortillas on top. Pour remaining 1/2 cup enchilada sauce over surface. Top with remaining cheese and olives if using.
08 - Cover dish with aluminum foil. Bake for 20 minutes.
09 - Remove foil and continue baking for 10 minutes until cheese is bubbly and golden brown.
10 - Let casserole rest for 5 minutes before serving. Top with cilantro, green onions, avocado, sour cream, and lime wedges.