Preheat oven to 350 degrees. Coat a 9” square pan with cooking spray. Glass or metal pan is fine.
In a large nonstick pan, cook the beef, onions, garlic, chili powder, and cumin over medium-high heat until onions are tender and beef is no longer pink. Stir often, breaking up the beef. Stir in black beans, undrained chile peppers, and mix well. Remove from heat and set aside.
In a small bowl, stir together sour cream, corn, cottage cheese, and garlic powder.
Place 4 tortillas, overlapping on the bottom of pan. Top with half the meat mixture, half the sour cream mixture, and half the enchilada sauce. Reserve topping ingredients until baked. Repeat layers.
Cover casserole with foil. Bake for 30-35 minutes, until heated through. Remove from oven, sprinkle with tomatoes, scallions, and cheese evenly over the top of the casserole. Bake uncovered for about 10 minutes until cheese is melted.
Remove from oven and let sit for about 10 minutes to set. Cut into 6 servings. Remove servings with a spatula Note: It holds together even better if baked and refrigerated overnight. Just before serving, heat in a 350-degree oven or microwave until hot. Cut into 6 slices.