Bring a pot of salted water to a boil and cook potatoes for 8–10 minutes until fork-tender. Drain and let cool slightly.
Mash potatoes until smooth and lump-free.
Mix in butter, salt, garlic powder, cream, pepper, egg, chives, and mozzarella until well combined.
Chill the mixture for 1 hour (or 30 minutes in freezer).
Scoop about 2 tablespoons and roll into balls.
Coat each ball in flour, then egg, then panko breadcrumbs.
Heat oil to 350°F (175°C).
Fry in batches for 2–3 minutes until golden brown.
Remove and drain on paper towels. Sprinkle with salt and serve warm.
These Potato Cheese Balls are best enjoyed hot while the cheese is perfectly melted.