HEAT oven to 400°F.
PLACE potatoes in 13x9-inch baking dish. Add 2 Tbsp. dressing; toss to coat. Bake 15 min. Meanwhile, toss peppers and onions with remaining dressing.
REMOVE baking dish from oven; push potatoes to sides of dish. Place chicken in center of dish. Combine mustard and basil; spread over chicken. Top evenly with pepper mixture.
BAKE 30 min. or until chicken is done (165ºF) and vegetables are tender. Top with cheese.