MIX meat and 2 Tbsp. of the dressing. Shape into four patties.

SPRAY large nonstick skillet with cooking spray. Add patties; cook on medium heat 5 min. on each side or until cooked through (160°F.) Top with Singles slices; cook 1 min. or until melted.

SERVE in buns with lettuce, tomato and remaining 2 Tbsp. dressing.