Mix thoroughly, 1 1/2 lbs. ground beef, 1 egg (beaten), 1 medium size onion (chopped), 1 teaspoon salt, and 1/8 teaspoon pepper. Shape meat mixture into a large square, about 3/4 inch thick. Cut into 6 equal portions. Arrange portions on broiler rack. Place in broiler with top of meat 2 inches from heat. Broil on front side 10 minutes. Turn and spread with mixture of 3/4 cup tomato sauce, 1 Tablespoon Parmesan cheese. Top portions with 6 slices of Mozzarella cheese. Broil until cheese is melted and lightly browned.
By Robin from Washington, IA