Preheat oven to 400º F.
In a large bowl, combine ground beef, onion, garlic, brown sugar, and Worcestershire sauce using two forks or your hands.
Season generously with salt and pepper, then work in breadcrumbs and egg.
Transfer ground beef to an 8-inch square baking dish and press it into an even layer.
Spread mashed potatoes on top of ground beef mixture, then top with cheddar cheese and bacon bits.
Cover baking dish with aluminum foil, then place in oven. Bake for 30 minutes, then remove aluminum foil and bake for another 10-15, or until cheese is melted and bubbly.
