HEAT large nonstick skillet sprayed with cooking spray on medium-high heat. Add chicken; cover. Cook 5 to 7 min. on each side or until done (165ºF). Remove chicken from skillet; cover to keep warm.
ADD cream cheese, water, pesto and tomatoes to skillet. Cook, uncovered, on medium heat 2 min. or until heated through, stirring occasionally.
RETURN chicken to skillet. Cook and stir 1 min. or until chicken is coated and heated through. Sprinkle with shredded cheese.