HEAT oven to 375ºF.
MIX cream cheese, spinach, 1 cup mozzarella and 3 tablespoons Parmesan until well blended; spread onto chicken breasts. Starting at one short end of each breast, roll up chicken tightly. Secure with wooden toothpicks, if desired.
BEAT egg in shallow dish. Mix remaining Parmesan and cracker crumbs in separate shallow dish. Dip chicken in egg, then roll in crumb mixture to evenly coat. Place, seam-sides down, in 13x9-inch baking dish sprayed with cooking spray.
BAKE 30 minute or until chicken is done (165ºF). Remove and discard toothpicks, if using. Serve chicken topped with spaghetti sauce and remaining mozzarella.
Make Ahead: Assemble chicken bundles and place in baking dish as directed. Refrigerate up to 4 hours. When ready to serve, uncover and bake at 375ºF for 35 minute or until chicken is done.
Special Extra: Stir chopped fresh basil and/or sliced black olives into spaghetti sauce before heating.
Nutrition Information Per Serving: 400 calories, 21g total fat, 10g saturated fat, 0.5g trans fat, 130mg cholesterol, 820mg sodium, 17g carbohydrate, 4g dietary fiber, 7g sugars, 38g protein, 140%DV vitamin A, 15%DV vitamin C, 40%DV calcium, 15%DV iron.