Preheat the 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 using thin-sliced chicken breasts, no need to slice them.) 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 plastic wrap or place it 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 dish, 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, Italian seasoning, garlic powder, salt, and pepper.

Coat the chicken first in the flour, then in the egg, and finally in the bread crumb mixture. Place the coated chicken on the prepared baking sheet or baking dish.

Bake the chicken in the upper third of the preheated oven for 12-15 minutes, or until the chicken is almost cooked through (it should register about 150°F when tested with an instant-read thermometer, as it will cook further after topping with the sauce and cheese). Spoon 2 tablespoons of marinara sauce over each chicken piece and sprinkle with mozzarella cheese. Continue baking until the chicken is fully cooked (it should reach 165°F at the thickest part when tested with an instant-read thermometer). This may take an additional 3-8 minutes, depending on the size of your chicken pieces.

Serve the chicken with pasta and additional marinara sauce, garnished with chopped fresh parsley or basil if desired.