Preparation of Potatoes :
Peel and mash the boiled potatoes until smooth.
Mixing the Puree :
In a bowl, mix the mashed potatoes with the egg yolks, grated Parmesan, chopped parsley, nutmeg, salt and pepper. Mix well until you get a smooth dough.

Preparation of the Cheese :
Cut the block of mozzarella into rectangles.
Formation of Donuts :
Take a few spoonfuls of mashed potatoes and form a patty. Place a rectangle of cheese in the center of the patty and wrap it completely with the mashed potatoes, forming a doughnut.
Coating the Donuts :
Beat the remaining 2 eggs in a bowl.
Dip each donut in beaten egg, then coat in breadcrumbs.
Cooking :
Heat oil in a skillet over medium heat.
Fry the donuts for 6-7 minutes or until evenly golden brown, turning occasionally for even cooking.
Service :
Drain the donuts on paper towels and serve hot.
Advice :
These donuts are ideal served with tomato sauce or garlic sauce.
Serve them warm to enjoy the soft cheese inside.