COOK chicken in large skillet sprayed with cooking spray on medium-high heat 2 to 3 min. on each side or until evenly browned. Remove from skillet.
ADD vegetables, water and garlic powder to skillet; bring to boil. Add stuffing mix; stir just until moistened.
TOP with chicken and cheese; cover. Cook on low heat 5 min. or until chicken is done (165ºF) and cheese is melted.