Heat oven to 400º. Cook beef and onions in ovenproof 12-inch skillet over medium heat 8 to 10 minutes, stirring occasionally, until beef is brown; drain. Stir in sloppy joe sauce. Sprinkle with cheese.
Stir remaining ingredients until blended. Pour over beef mixture. If skillet is not ovenproof, cover handle with aluminum foil.
Bake uncovered about 30 minutes or until golden brown.