Preheat the oven to 375°F. Lightly grease a 9×13-inch baking dish.
Add the ground beef and diced onion to a large skillet over medium-high heat. Cook, breaking the beef into crumbles, until browned and the onion is softened. Add the garlic and cook for 30 seconds. Drain excess fat.
Stir the chili powder, cumin, paprika, salt, and black pepper into the ground beef.
Add the drained black beans and 1 cup of enchilada sauce. Stir and cook for 2–3 minutes, then remove from the heat.
Cut the corn tortillas into halves or quarters to make layering easier.
Spread about 1/2 cup enchilada sauce over the bottom of the prepared baking dish. Arrange a layer of corn tortillas over the sauce, overlapping as needed.
Spread half of the beef and bean mixture over the tortillas and sprinkle with about one-third of the cheese.
Add another tortilla layer, followed by the remaining beef mixture and another one-third of the cheese.
Finish with a final layer of tortillas. Pour the remaining enchilada sauce evenly over the top and sprinkle with the remaining cheese.
Cover loosely with aluminum foil and bake for 20 minutes. Remove the foil and bake for another 10–15 minutes, until the cheese is melted and the sauce is bubbling around the edges.
Remove from the oven and let the casserole rest for 10 minutes before slicing and serving.

Corn tortillas work best because they hold their structure better after baking.

Drain the ground beef well to prevent the casserole from becoming greasy.

Drain and rinse the black beans thoroughly before adding them to the filling.

Cutting the tortillas into halves or quarters makes it easier to cover the baking dish without leaving large gaps.

For a milder casserole, use mild red enchilada sauce. For more heat, use medium or hot enchilada sauce.

Cheddar and Monterey Jack can be replaced with Colby Jack or another good melting cheese.

Let the casserole rest for about 10 minutes after baking so the layers can settle before slicing.

Store leftovers in an airtight container in the refrigerator for 3–4 days.

Ground beef should reach a safe minimum internal temperature of 160°F.