Preheat the oven to 400 degrees F. In a medium skillet brown the ground beef with the onions over medium-high heat. Drain. Season with salt, pepper and garlic powder. Stir in ketchup and mustard.
Grease a 9-inch square baking dish with cooking spray. Spoon the beef mixture into the baking dish. Top with bacon, tater tots, and shredded cheese.
Place into the oven and bake for 30-35 minutes or until heated through and the tater tots are golden brown.