Place chicken breasts between 2 pieces of wax paper or plastic wrap; slightly flatten the chicken using the palm of your hand and pres down on the thickest part. Brush each side of chicken with 1 Tbsp. Garlic Parmesan Wing Sauce. Grill chicken until no longer pink. During last 1-2 minutes of cooking time, place hamburger buns, cut side down, on grill; cook until lightly toasted.
Combine dressing and celery. Place chicken on buns and top with dressing.