Heat oven to 350. Brown ground beef with onion in large nonstick skillet over medium heat 8-10 minutes or until beef is not pink. Pour off drippings.
Stir in Sloppy Joe sauce, pasta and water. Transfer to greased 13x9 -inch baking dish. Bake, covered, in 350 oven 35-40 minutes or until pasta is tender. Top with cheese. Bake, uncovered, 5 minutes or until cheese is melted. Let stand 5 minutes.