Preheat oven to 350ºF.
Combine beef, onion, bell pepper, and garlic in a large skillet. Cook until no pink remains. Drain any fat.
Add taco seasoning and ¼ cup water. Simmer until the water evaporates. Stir in enchilada sauce.
Transfer the beef mixture to a 2-quart baking dish. Top with 1 ½ cups of cheese.
In a medium bowl, combine corn muffin mix, sour cream, corn, milk, and egg. Spread overtop of the beef mixture.
Top with remaining cheese and bake 35-40 minutes.
Garnish with cilantro and serve.
