PREHEAT barbecue to medium heat. Mix meat and 2 Tbsp. of the dressing. Shape into 8 thin patties. Mix remaining 1 Tbsp. dressing and the bacon bits. Spoon about 1 Tbsp. of the bacon mixture onto centre of each of 4 of the patties; top with 2 Singles quarters and second patty. Pinch edges of patties together to seal.
GRILL patties 7 to 9 min. on each side or until cooked through (160°F).
COVER bottom halves of buns with lettuce and burgers. Top with tomatoes and top halves of buns.