Mix meat and 2 Tbsp. dressing; shape into 4 (1/2-inch-thick) patties.
Cook in nonstick skillet sprayed with cooking spray on medium heat 4 to 5 min. on each side or until done (160F). Top with 2% Milk Singles; cook 1 min. or until melted.
Serve, topped with remaining dressing, in buns with lettuce and tomatoes.