Preheat the oven to 350°F.
Prepare the baking dish by misting it with cooking spray. (A 10.5 x 7.5-inch casserole dish (11x7) was used, but an 8 x 8-inch square pan works well too. A 9 x 13-inch pan will make the casserole thinner and require more cornbread mix to cover it. If using a 9 x 13, increase the ingredients by half and use 16 oz. of cornbread mix.)
cooking spray
Brown and crumble the ground beef in a large skillet over medium-high heat until fully cooked and no longer pink. Add the diced onion and cook for about 5 minutes, until softened.
1-1/2 lbs. ground beef (93% lean), 1 medium yellow onion, diced
Stir in the taco seasoning and water, cooking for one minute. Remove from heat and drain any excess grease if needed.
1 oz. taco seasoning, 3 tbsps. water
Add the corn, enchilada sauce, chiles, and ½ cup of shredded cheese to the meat mixture. Stir until combined, then spread it evenly in the bottom of the baking dish.
1 (15 oz.) can yellow corn, 1 (15 oz.) can red enchilada sauce , 1 (4 oz.) can diced green chiles, 1-1/2 cups shredded Mexican cheese, divided
Prepare the cornbread mix according to the package directions (uses milk and egg - do not bake), then spread it evenly over the meat mixture using a large spoon or flat spatula.
1 (8.5 oz.) box cornbread mix, such as JIFFY
Sprinkle the remaining cheese over the top of the cornbread mixture.
Bake for 30–40 minutes, until bubbling and the cornbread is fully cooked (a toothpick inserted in the center should come out clean).
Slice and serve warm, topped with sliced green onions or any other toppings you like.
garnish: sliced green onions (optional)