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