1Heat gas or charcoal grill. In large bowl, combine ground beef, ketchup and sloppy Joe seasoning mix; mix gently. Shape mixture into 6 patties, 1/2 inch thick.
2When grill is heated, carefully oil grill rack. Place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cover grill; cook 13 to 15 minutes or until meat thermometer inserted in center of patties reads 160°F., turning once. During last 1 to 2 minutes of cooking time, place cheese on patties; cook until melted. Serve patties in buns.