Heat the oven to 350 degrees.
Layer half of the tortillas in the bottom of a 9x9 baking dish.
Mix together the sour cream, garlic powder, cream of chicken soup, green chilis, onion powder and salt and pepper to taste in a large mixing bowl.
Place half of the shredded chicken over the tortillas in the baking dish.
Spread half of the soup mixture over the chicken, and top with 1 cup of shredded cheese.
Add another layer of tortillas, the remaining chicken, then soup mixture, and finally, the rest of the cheese on top.
Bake for 40 minutes.
Rest for 15-20 minutes before serving.