In a medium nonstick skillet over medium heat, cook the ground beef and onions until the beef is no longer pink (8-10 minutes). Drain grease. Stir in the garlic powder, mustard, ketchup, salt, pepper, and water, mixing until combined.
Assembly:
Divide the sloppy joe mixture between both sides of the loaves and top with the mozzarella and cheddar cheese. Bake for 12-14 minutes or until golden brown.
Cut into pieces and serve with parsley for garnish.
