Yield: 4 servings
Flatten chicken thighs to about 1/4-inch thickness between waxed paper or plastic wrap. Mix egg and water. Mix bread crumbs and Parmesan cheese. Dip chicken into egg mixture, coat with bread crumb mixture.
Heat oil in a 10-inch skillet over medium heat until hot. Cook chicken in oil about 12 minutes, turning once, until juice of chicken is no longer pink when centers of thickest pieces are cut. (Add additional oil during cooking, if necessary.) Remove skillet from heat.
Sprinkle mozzarella cheese over chicken; let stand 1 minute. Spoon spaghetti sauce over cheese. Serve chicken on toasted bread.
Please note that some ingredients and brands may not be available in every store.