Preheat oven to 425° F. Grease a baking sheet or baking dish with cooking spray or oil.
Slice the chicken breasts in half horizontally to get 4 thin chicken cutlets. If the chicken cutlets are uneven in thickness, you can pound them with a meat mallet or rolling pin to make them an even ½-inch thickness. (Cover the chicken with a piece of plastic wrap or place in a zip-top bag before pounding to prevent splattering.)
To prepare the breading for the chicken, you will need 3 shallow pie plates, bowls or other wide and shallow dishes. In one, place the flour. In the second, place the egg and tablespoon of water. Use a fork to beat the egg and water together until well combined. In the third dish, stir together the Italian seasoned bread crumbs, Parmesan cheese, salt and pepper.
Coat the chicken first in the flour, then in the egg, and then in the bread crumb mixture. Place on the prepared baking sheet or baking dish.
Bake chicken in the upper third of the preheated oven for 12-15 minutes, or until the chicken is almost cooked through (it should be about 150° F when tested with an instant read thermometer). Spoon 2 tablespoons of the marinara sauce over each chicken piece and sprinkle with the mozzarella cheese. Continue baking chicken until it is cooked through (it should register 165° F at the thickest part when tested with an instant read thermometer). This may take about 3 to 8 minutes, depending on the size of your chicken pieces.
Serve chicken with pasta and additional marinara sauce, garnished with chopped fresh parsley or basil if desired.