COOK spaghetti as directed on package, omitting salt.
MEANWHILE, heat dressing in large nonstick skillet on medium-high heat. Add chicken; cook and stir 2 min. Add zucchini; cook 2 min., stirring frequently. Stir in spaghetti sauce. Bring just to boil, stirring occasionally. Simmer on medium-low heat 5 min. or until chicken is done. Add Neufchatel; cook 1 min. or until Neufchatel is melted and mixture is well blended, stirring occasionally.
DRAIN spaghetti. Serve topped with chicken mixture and Parmesan.