Mexican Quesadilla Casserole

Step 1
Preheat oven to 350 degrees F (175 degrees C). Prepare a 13×9-inch baking dish with cooking spray.

Step 2
Heat a large skillet over medium-high heat. Cook and stir beef and onion in the hot skillet until beef is completely browned, 5 to 7 minutes; drain and discard grease.

Step 3
Stir tomato sauce, black beans, diced tomatoes with lime juice and cilantro, corn, and chopped green chiles into the ground beef mixture; season with chili powder, cumin, garlic, oregano, and red pepper flakes. Reduce heat to low and cook mixture at a simmer for 5 minutes.

Step 4
Spread about 1/2 cup beef mixture into the bottom of the prepared baking dish; top with 3 tortillas, overlapping as needed. Spread another 1/2 cup beef mixture over the tortillas. Sprinkle 1 cup Cheddar cheese over beef. Finish with layers of remaining tortillas, beef mixture, and Cheddar cheese, respectively.

Step 5
Bake in preheated oven until heated throughout and the cheese is melted, about 15 minutes. Cool 5 minutes before serving.