Heat oven to 350°. Heat large nonstick skillet over medium heat until hot. Add ground beef and yellow onion; cook 8 to 10 minutes, breaking into 3/4-inch crumbles and stirring occasionally. Pour off drippings. Stir in sloppy Joe sauce, rotini and water. Spray 13 by 9-inch glass baking dish with nonstick cooking spray. Spoon beef mixture into dish; cover with aluminum foil. Bake in 350° oven 35 to 40 minutes or until pasta is tender. Uncover; sprinkle with cheese. Continue baking, uncovered, 5 minutes or until cheese is melted. Let stand 5 minutes before serving. Garnish with green onions, if desired.