1. In a large skillet cook the ground beef, onion, chili powder, and cumin until onion is tender and meat is no longer pink; drain. Stir pinto beans and undrained chili peppers into meat mixture; set aside.
2. In a small mixing bowl stir together sour cream, flour, and garlic powder until combined; set aside.
3. Place half of the tortillas in the bottom of a lightly greased 2-quart rectangular baking dish, cutting to fit if necessary. Top with half of the meat mixture, half of the sour cream mixture, and half of the enchilada sauce. Repeat layers. Cover dish with plastic wrap; chill in refrigerator for up to 24 hours.
4. To serve: Preheat oven to 350F. Remove plastic wrap; cover dish with foil. Bake in preheated oven for 35 to 40 minutes or until bubbly. Uncover; sprinkle with cheese and bake 5 minutes more. Makes 6 to 8 servings.