1Heat oven to 425°F. Line 15x10x1-inch baking pan with foil; spray foil with nonstick cooking spray. In large bowl, beat egg. Stir in all remaining ingredients.
2In sprayed foil-lined pan, shape beef mixture into 8-inch square. Cut into 25 squares; do not separate.
3Bake 20 to 25 minutes or until meatballs are thoroughly cooked and no longer pink in center. With sharp knife, cut apart meatballs.