In a large skillet, cook beef over medium heat until no longer pink; drain and place in a bowl. Add the brown sugar, ketchup, Worcestershire sauce, mustard, salt, pepper and garlic powder.
Prepare cornbread mix according to package directions. Fill greased muffin cups with a scant 2 tablespoons of batter. Top each with 2 tablespoons beef mixture; sprinkle with cheese. Top with remaining cornbread mix.
Bake at 400° for 12-15 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Serve warm. Refrigerate leftovers.