Heat the oven to 425°F. Slice the chicken breasts horizontally into four cutlets, place them between sheets of plastic wrap, and gently pound them to an even thickness of about ½ inch.

Season both sides of the chicken with the divided kosher salt and black pepper. Set out three shallow bowls: flour in the first, beaten eggs mixed with water in the second, and breadcrumbs mixed with ¼ cup Parmesan, Italian seasoning, and garlic powder in the third.

Dredge each cutlet in flour, shaking off the excess. Dip it into the egg mixture, then press it firmly into the breadcrumb mixture so the coating covers every surface.

Heat the oil in a large oven-safe skillet over medium-high heat. Cook the breaded chicken for about 2–3 minutes per side, working in batches if needed, until the coating is golden brown.

Spoon the marinara sauce into the skillet and around the chicken. Keep most of the sauce underneath or beside the cutlets instead of completely covering the crispy tops.

Sprinkle the chicken with the shredded mozzarella and the remaining Parmesan. Transfer the oven-safe skillet to the 425°F oven and bake for 12–15 minutes.

Check the thickest part of the chicken with an instant-read thermometer; it should reach 165°F. If desired, broil for 1–2 minutes at the end, watching closely, until the cheese is lightly browned and bubbling.

Remove the skillet from the oven and rest the chicken for about 5 minutes. Garnish with chopped parsley or basil, then serve with pasta, salad, or garlic bread.