Preheat oven to 400°. Grease a 9 x 13 Pyrex dish with cooking spray. In a large bowl, whisk together corn muffin mix, egg, sour cream, and creamed corn. Transfer to prepared skillet and bake until golden, 20 minutes. Let cool.
Meanwhile, in a large skillet over medium heat, heat oil. Add onion, cumin, and chili powder and season with salt and pepper. Cook until soft, 5 minutes. Add garlic and cook until fragrant, 1 minute more. Add ground beef and cook, breaking up meat with a wooden spoon, until no longer pink, about 6 minutes. Drain fat.
Poke entire surface of cornbread with a fork and pour over enchilada sauce. Add beef and top with cheeses.
Cover with foil and bake until cheese is melty, about 20 minutes. Switch oven to broil, remove foil, and broil until cheese turns golden, about 5 minutes.