Preheat oven to 350 degrees. Lightly grease a medium baking sheet.
Between two sheets of wax paper, flatten chicken breasts to 1/4-inch thickness.
Beat eggs in a small shallow dish. Place Italian bread crumbs and 1/2 cup Parmesan cheese in a separate shallow dish.
Dip chicken into egg, then into the bread crumbs. Place coated chicken on the prepared baking sheet and bake in the preheated oven for 40 minutes, or until no longer pink and juices run clear.
Pour 1/2 of the spaghetti sauce into a baking dish. Place chicken over sauce, and cover with remaining sauce. Place one slice of mozzarella cheese over each chicken breast and sprinkle with Parmesan cheese. Return to oven for 10-15 minutes or until cheese is melted.