Preheat the oven to 350°F (175°C).
In a large skillet over medium heat, cook the ground beef until browned. Drain excess fat if necessary.
Add the chopped onion and minced garlic to the skillet with the beef. Sauté until the onion is translucent, about 5 minutes.
Stir in the taco seasoning, black beans, corn, and 1 cup of enchilada sauce. Cook for another 2-3 minutes until heated through.
In the baking dish, spread a thin layer of enchilada sauce on the bottom.
Place 4 tortillas on top of the sauce, covering the bottom of the dish.
Layer half of the beef mixture over the tortillas, followed by half of the shredded cheddar and Monterey Jack cheese.
Repeat the layers: tortillas, remaining beef mixture, and top with the remaining cheese.
Pour the remaining enchilada sauce over the top of the casserole, ensuring the tortillas are well covered.
Cover the dish with aluminum foil and bake in the preheated oven for 20 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and lightly browned.
Let it cool for a few minutes before serving. Top with optional toppings like sour cream, cilantro, or jalapeños if desired.