PREHEAT oven to 400ºF. Cook spaghetti in large saucepan as directed on package.
MEANWHILE, place chicken on foil-covered baking sheet. Mix mayo and Parmesan cheese; spread onto chicken. Top evenly with cracker crumbs. Bake 18 to 20 min. or until chicken is cooked through (165ºF).
DRAIN spaghetti in colander. Meanwhile, cook spaghetti sauce in same saucepan on medium heat 5 min. or until heated through, stirring occasionally. Spoon 1 cup of the sauce evenly over chicken; top with mozzarella cheese. Bake an additional 2 min. or until cheese is melted. Add spaghetti to sauce; toss to coat. Serve with the chicken.