Preheat grill to medium heat. Remove plank from water; brush tops with oil. Place 2 chicken breasts on the plank. Place on grate of grill; cover with lid. Grill for 30 min.
Meanwhile, mix dressing, honey, mustard and seasonings until well blended. Remove 1/2 cup of the dressing mixture to serve with the cooked chicken. Brush chicken with some of remaining dressing mixture.
Grill, covered, an additional 30 to 45 min. or until chicken is cooked through (165ºF), brushing occasionally with the remaining dressing mixture. Remove chicken from grill; discard plank. Serve with the reserved dressing mixture.
