Serves: 8 Combine first 7 ingredients and shape into patties. Set aside. To make sauce, saute onion slices in 3 Tbsp butter or margarine until soft. Add remaining ingredients for sauce. Place patties in large baking pan in single layer and pour sauce over. Cover pan with aluminum foil and bake one hour at 375F. After baking, remove foil, sprinkle each patty generously with the Mozzarella cheese and return to oven until cheese is melted.