Preheat oven to 375 degrees and spray a 9x13 baking dish with cooking spray.
In a large skillet, brown the beef; when the beef is nearly done add the onion. Cook the onion till soft and the beef is cooked through. Add the garlic and let cook for about one minute. Drain any fat from skillet.
Add the can of green chiles, taco seasoning, black beans, corn, and 2 cups of the cheese.
Stir together to combine then pour mixture into the prepared baking dish.
Arrange tater rounds or tots on top of the mixture in a single layer.
Pour the enchilada sauce on top of the casserole, covering all of the tator rounds or tots.
Bake uncovered for 30-40 minutes or until the top is nice and crispy.
Sprinkle the remaining 1 cup of cheese on top and place back in the oven for 2-3 minutes or until cheese has melted. Remove from oven and serve.
Top with your favorite taco toppings.