Combine the filling: Add browned ground beef, corn, soup, sour cream, cheese, onion, garlic powder, salt, and pepper. Stir to combine.
1 pound ground beef, 1 can (15-ounce) corn, 1 can (10.5 ounce) cream of mushroom or cream of chicken soup, ½ cup sour cream, 1 ½ cups shredded cheddar cheese, 1 teaspoon garlic powder, Salt and pepper to taste, 1 small onion