Peel and cut the potatoes into 2-inch cubes. Boil them in salted water until fork-tender.
In a mixing bowl, mash the potatoes. Add corn starch, salt, pepper, garlic powder, dried parsley, and Parmesan cheese. Mix thoroughly until it starts to form a dough.
Take some potato filling, flatten it, and add a square of mozzarella cheese. Close it to form a ball shape. Repeat this process with the remaining potato filling to form balls and set them aside.
In a separate bowl, make the dry batter. Add all-purpose flour, flour, cornstarch, salt, black pepper, and garlic powder. Mix well and set aside.
In another bowl, make the egg wash by whisking together eggs and water.
In a third bowl, combine panko breadcrumbs and parsley.
Dip each potato ball in the dry batter, then in the egg wash, and finally in the panko breadcrumb mixture, coating them evenly.
Heat the oil to 350°F. Fry the potato balls in batches for 2 to 3 minutes, or until they are golden brown and crispy.
Sprinkle some more Parmesan cheese on top before serving and enjoy.
