#1 Heat grill to medium-high heat #2 Shape meat into 8 thin patties. Place 1 Tbsp. cheese on center of each patty press meat around cheese to completely enclose cheese. Roll each into ball, then flatten into 1/4-inch-thick patty #3 Grill 3 to 5 min. on each side or until done, adding buns, cut sides down, to grill to toast for the last 2 min #4 Place lettuce, tomatoes and onions on bottom halves of buns top with burgers and ketchup. Cover with tops of buns.