Preheat Oven: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish with cooking spray.
Prepare the Filling: In a large skillet over medium heat, cook the ground beef or turkey until browned. Add the chopped onion, bell pepper, and garlic. Cook until the vegetables are tender, usually about 5-7 minutes.
Add Beans, Corn, and Seasonings: To the skillet, add the black beans, corn, diced tomatoes, green chilies, taco seasoning, cumin, chili powder, salt, and pepper. Stir well to combine. Allow the mixture to simmer for 5-7 minutes to let the flavors meld together. Taste and adjust seasoning if needed.
Layering the Casserole: Place a layer of tortillas on the bottom of the prepared baking dish, ensuring they cover the entire base. Spread half of the meat mixture evenly over the tortillas. Sprinkle a generous portion of shredded cheese over the meat mixture. Repeat with another layer of tortillas, the remaining meat mixture, and top with a final layer of tortillas. Sprinkle the remaining cheese on top.
Baking: Cover the dish with foil and bake in the preheated oven for 25-30 minutes or until the cheese is melted and bubbly.
Serve: Once done, remove the foil and let it sit for a few minutes. Cut into squares and serve warm. Top individual servings with chopped green onions, sliced jalapeños, sour cream, salsa, or guacamole, as desired.
