HEAT large skillet sprayed with cooking spray on medium-high heat. Add chicken; cover. Cook 2 min. on each side or until browned.
ADD vegetables, Macaroni, Cheese Sauce Mix, water and 1/2 cup of the cheese; stir. Bring to boil; cover. Reduce heat to low; simmer 12 min. or until chicken is cooked through (165ºF), stirring occasionally.
SPRINKLE with remaining 1/2 cup cheese; cover. Let stand 5 min.