Preheat the oven to 375 degrees. Lightly grease a 9x9 inch baking dish and set it aside.
In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is soft. Drain any excess fat.
Add the minced garlic, chili powder, cumin, cayenne pepper, salt, and black pepper to the skillet. Stir and cook for one minute until fragrant.
Pour in the enchilada sauce and add the black beans. Stir everything together and let it simmer for two minutes.
Spread a thin layer of the beef mixture in the bottom of the prepared baking dish. Arrange half of the tortilla pieces over it, then sprinkle with one cup of cheese.
Add the remaining beef mixture and top with the rest of the tortilla pieces. Finish with the remaining cup of cheese.
Bake for 20 minutes until the cheese is melted and the edges are bubbling. Let the casserole rest for five minutes before serving with sour cream and cilantro.