Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish with olive oil or cooking spray.

In a medium bowl, combine the shredded chicken, sour cream, green enchilada sauce, diced green chilies, garlic powder, onion powder, cumin, salt, and black pepper. Mix well until evenly combined.

Spread a thin layer of the chicken mixture on the bottom of the prepared baking dish.

Cut the corn tortillas into halves or quarters for easier layering. Place a layer of tortillas over the chicken mixture, ensuring they slightly overlap.

Spread another layer of the chicken mixture over the tortillas, followed by a layer of shredded Monterey Jack cheese and cheddar cheese.

Repeat the layering process (tortillas, chicken mixture, cheeses) until all ingredients are used, finishing with a generous layer of shredded cheese on top.

Cover the casserole dish with aluminum foil and bake in the preheated oven for 20 minutes.

Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbling.

Remove the casserole from the oven and let it cool for 5 minutes before serving.

Garnish with fresh cilantro if desired, and serve warm.