HEAT large skillet sprayed with cooking spray on medium-high heat. Add chicken; cover. Cook 2 min. on each side or until browned on both sides.
ADD vegetables, Macaroni, Cheese Sauce Mix, water and 1/2 cup shredded cheese; stir. Bring to boil; cover. Simmer on low heat 12 min. or until chicken is done (170ºF), stirring occasionally.
SPRINKLE with remaining shredded cheese; cover. Let stand 5 min.