Mix cream cheese, rosemary, half the garlic and pepper. Starting at neck of chicken, use handle of wooden spoon or fingers to carefully separate skin from meat of breast, thighs and legs, being careful not to tear the skin. Spoon cream cheese mixture under skin; use fingers to spread mixture out to thighs and legs.
Place lemon halves into cavity of chicken.
Place chicken in shallow pan.
Brush with 2 Tbsp. oil.
Toss potatoes with remaining oil and garlic in separate pan.
Bake chicken and potatoes 1-1/4 to 1-1/2 hours or until chicken is done (165 F), stirring potatoes every 30 min.
Transfer chicken to large serving dish, reserving juices in pan.
Let chicken stand 10 min. Spoon potatoes around chicken. Skim fat from reserved juices in pan; discard fat. Spoon juices over chicken and potatoes.