Cut each mozzarella string cheese stick in half to make 24 shorter pieces.
Place the mozzarella pieces on a tray and freeze for 20 minutes while preparing the breading.
Add the flour to one shallow bowl.
Whisk the eggs and water together in a second shallow bowl.
In a third bowl, combine the panko, Italian breadcrumbs, Parmesan, garlic powder, onion powder, Italian seasoning, salt, and black pepper.
Coat each piece of mozzarella in flour and shake off the excess.
Dip the floured cheese into the egg mixture, then press it into the breadcrumbs until fully coated.
Dip the breaded cheese into the egg again and coat it with breadcrumbs a second time. Press the coating firmly around the ends.
Arrange the breaded mozzarella sticks on a parchment-lined tray and freeze for at least 1 hour, or until completely solid.
Preheat the oven to 425°F with a baking sheet inside.
Remove the hot baking sheet, line it with parchment paper, and arrange the frozen mozzarella sticks in a single layer.
Lightly spray the sticks with cooking spray.
Bake for 7 to 9 minutes, checking frequently after 6 minutes. Remove them when the coating is crisp and the cheese is softened but not leaking.
Rest for 1 to 2 minutes and serve immediately with warm marinara sauce.
