Prepare the Filling:

Cook Ground Beef: In a large skillet over medium heat, cook the ground beef until browned, breaking it into crumbles as it cooks. Drain excess fat.

Add Aromatics: Stir in the onion and garlic and cook for 2-3 minutes until softened.

Season and Combine: Add the taco seasoning, black beans, and half of the enchilada sauce. Stir well to combine. Remove from heat.

Assemble the Casserole:

Preheat Oven: Preheat your oven to 375°F (190°C).

Layer the Ingredients: In a 9x13-inch baking dish, spread a thin layer of enchilada sauce on the bottom. Add a layer of tortilla quarters, followed by a layer of the beef mixture, and then a layer of cheese. Repeat the layers, finishing with a layer of cheese on top.

Bake:

Bake the Casserole: Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbly.

Garnish and Serve:

Add Toppings: Remove from the oven and let the casserole cool for 5 minutes. Garnish with diced tomatoes, cilantro, and green onions, if desired.

Serve: Slice and serve warm with sour cream, guacamole, or salsa on the side.