Preheat oven to 400° F. Spray a large casserole dish with non-stick cooking spray. Set aside.
In a large bowl, combine corn muffin mix, egg, sour cream and creamed corn until well mixed together.
Pour batter into prepared baking dish and bake for 20 minutes, until golden brown.
Remove from oven and allow to cool.
In a large skillet over medium heat sautee onion in vegetable oil until soft. Add taco seasoning mix and stir to combine.
Add ground beef and minced garlic breaking up the beef with a wooden spoon as it cooks. Drain off excess fat.
Stir in ½ of the enchilada sauce and cook until meat and sauce has thickened. Remove from heat.
Using a fork prick the entire surface of the baked cornbread crust in the baking dish.
Spread the remaining ½ of the enchilada sauce evenly over the cornbread.
Spread the ground beef mixture over the cornbread crust.
Top with shredded cheeses.
Cover casserole dish with foil and bake for 20 minutes.
Remove foil and set oven temperature to broil.
Broil until cheese is melted and golden brown along the edges.
Top each serving with shredded lettuce, chopped tomato and sour cream.