PREHEAT oven to 400°F. Mix soup and 2 Tbsp. of the water; set aside. Combine stuffing mix and remaining water; spoon evenly onto centre of each of four large sheets of heavy-duty foil. Top each with one chicken breast. Cover evenly with the ham, mushrooms, peas and soup mixture.
BRING up foil sides. Double fold top and both ends to seal each packet, leaving room for heat circulation inside. Place packets in single layer in 15x10x3/4-inch baking pan.
BAKE 30 to 35 min. or until chicken is cooked through (170°F). Remove packets from oven; let stand 5 min. Place one packet on each of four dinner plates. Cut slits in foil with sharp knife to release steam before opening.