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

In a large mixing bowl, combine the shredded chicken, sour cream, 1/2 cup of the green chili enchilada sauce, diced green chilies, garlic powder, onion powder, and salt and pepper to taste. Mix until fully combined.

Spread a thin layer of the remaining green chili enchilada sauce on the bottom of the prepared baking dish.

Layer 3-4 corn tortillas on top of the sauce, tearing them if necessary to cover the entire surface.

Spread half of the chicken mixture evenly over the tortillas, followed by 1/3 of the shredded Monterey Jack and cheddar cheeses.

Add another layer of tortillas, followed by the remaining chicken mixture and another 1/3 of the cheeses.

Top with a final layer of tortillas, the remaining green chili enchilada sauce, and the rest of the shredded cheeses.

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

Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.

Let the casserole cool for 5 minutes. Garnish with chopped cilantro if desired, and serve warm.