Sour Cream Enchilada Casserole

Brown ground beef in skillet over medium-high heat; drain and season to taste garlic powder, salt and pepper. In a bowl, combine sour cream, green chilies and soup. Spread about 1 cup sauce in bottom of a lightly greased 13 x 9 x 2-inch baking pan. Place 4 tortillas over soup mixture. Layer with meat mixture, onions, and 1/2 of the cheese. Place remaining of tortillas on top and spoon remaining soup mixture over tortillas. Sprinkle with remaining cheese. Cover and bake at 375° F (190 °C) for 20 minutes. Remove cover and bake for additional 10 minutes.