Cook pasta according to package directions, including salt. Drain pasta, and keep warm.
Chicken should be skinned and boned.
Place each chicken breast half between 2 sheets of heavy-duty plastic wrap: flatten to ¼-inch thickness, using a meat mallet or rolling pin.
Combine breadcrumbs and parmesan cheese in a shallow dish. Dredge 1 chicken breast half in flour.
Dip in egg; dredge in breadcrumb. Repeat procedure with remaining chicken, flour, egg, and breadcrumb mixture.
Heat oil in a large nonstick skillet over medium-high heat. Add chicken; cook 4 minutes on each side or until done.
Place spaghetti evenly on each of 4 gratin dishes. Spoon ½ cup pasta sauce over each serving. Top each with 1 chicken breast half. Spoon ¼ cup sauce over each serving. Sprinkle each serving with ¼ cup mozzarella cheese.
Place gratin dishes on a baking sheet; broil 4 minutes or until cheese melts. Garnish with basil sprigs, if desired. Yield: 4 servings.