Preheat the oven to 350°F (175°C). In a skillet, combine the shredded chicken, black beans, corn, cumin, garlic powder, and onion powder. Stir until well mixed and heated through.

In a 9x13 inch baking dish, spread a thin layer of enchilada sauce on the bottom. Layer half of the tortilla strips, followed by half of the chicken mixture, half of the cheese, and half of the enchilada sauce. Repeat the layers.

Cover the baking dish with foil and bake for 20 minutes. Remove the foil, add the remaining cheese on top, and bake for an additional 10 minutes or until the cheese is bubbly and golden.

Let the casserole cool for a few minutes before serving. Top with sour cream if desired.