Make the Beef Filling
In a large skillet over medium heat, cook the ground beef until fully browned. Drain excess fat, then add corn, kidney beans, salsa, taco seasoning, water, salt, black pepper, and garlic powder. Stir and let the mixture simmer for 5–7 minutes until slightly thickened and well combined.

Mix the Cornbread Topping
In a mixing bowl, combine the Jiffy corn muffin mix, creamed corn, milk, and sour cream. Stir until just combined avoid overmixing to keep the topping tender.

Assemble the Casserole
Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish. Pour the beef filling evenly into the dish. Sprinkle 1 cup of shredded cheese over the top of the filling. Gently spoon and spread the cornbread mixture over the top.

Bake
Bake uncovered for 25–30 minutes, or until the cornbread is golden brown and cooked through. A toothpick inserted in the center should come out clean.

Rest and Serve
Let the casserole sit for 10–15 minutes before serving. This allows the layers to firm up and makes slicing easier. Serve with sour cream, chopped cilantro, or sliced jalapeños if desired.