HEAT oven to 350°F. Wash and pat chicken dry with paper towels. Using fingers or end of wooden spoon, separate skin from meat on both sides of chicken, being careful not to tear the skin.
BRUSH bottom of chicken with 1/4 cup dressing. Tuck wings under chicken; place, breast-side up, on rack in roasting pan. Brush or pour 1/2 cup of the remaining dressing under the skin and on outside surface of chicken. Combine carrots, celery and remaining dressing; spoon into chicken cavity.
BAKE 1-1/2 to 2-1/2 hours or until chicken is done (165°F). Let stand 10 min. before serving. Meanwhile, remove and discard vegetables from chicken cavity.