Use fingers or end of wooden spoon to 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 hours or until chicken is done (165°F). Let stand 10 min. before serving. Meanwhile, remove and discard vegetables from chicken cavity.