Heat large nonstick skillet sprayed with cooking spray on med-high heat. Add chicken;cover chicken with lid. Cook 5-7 minutes on each side or until chicken is cooked through (165°). Remove chicken from skillet;keep warm.
Reduce heat to medium. Add cream cheese, water, pesto, and tomatoes to skillet. Cook uncovered 2 minutes or until sauce is creamy and smooth.
Return chicken to skillet. Cook and stir 1 minute or until chicken is coated and heated through. Sprinkle with shredded cheese.