Heat oven to 375 degrees F. Mix cream cheese, 1 tsp. rosemary and 1/2 tsp. pepper. Starting at neck of chicken, use handle of wooden spoon or fingers to carefully separate skin from meat of the breast, thighs and legs of chicken, being careful to not tear the skin. Spoon cream cheese mixture under skin; use fingers to push and spread some of the mixture out to thighs and legs. Place chicken in shallow baking pan. Brush with 2 Tbsp. dressing.
Toss potatoes with remaining dressing, rosemary and pepper in separate pan. Bake chicken and potatoes 1-1/4 hours or until chicken is done (165 degrees F), stirring potatoes every 30 min.
Transfer chicken to large serving dish, reserving juices in pan. Let chicken stand 10 min. Meanwhile, add bacon and onions to potatoes; mix lightly. Spoon around chicken in dish. Skim fat from reserved chicken juices in pan; discard. Spoon juices over chicken and potatoes.