In a bowl, mix the ground beef, egg, Parmesan cheese, parsley, salt, and pepper.
3. Step
Take a piece of the meat mixture of about the size of a ping pong ball and slightly flatten it. Add a piece of mozzarella cheese in the center, and seal it with your hands.
4. Step
Bake for 15 minutes.
5. Step
Cover a meat ball with a layer of mashed potatoes, and mold it with your hands, continue molding it into a ball.
6. Step
Dip the meatball in a bowl of flour. Repeat with remaining meatballs.
7. Step
Heat the oil to 350ºF (180ºC). Fry the mashed potato-covered meatballs in batches until golden brown.
8. Step
Transfer to a paper towel-lined plate.
9. Step
Sprinkle with chopped parsley and serve with marinara sauce.
