Wash the sprouts, cut a cross on the flat of each stem, then cook them in boiling salt water for 6-8 minutes.
Mix the ground beef, onion, and paprika together, then shape the meat into small balls that are roughly the size of the sprouts. Brown them in some oil.
Put the cooked potatoes in a bowl with the milk, butter, some nutmeg, and a pinch of salt and pepper and mash it all together. Break the egg into the bowl and fold it into the potato.
Arrange the sprouts and the meatballs in a circular dish and then spread the mashed potato on top. To finish, sprinkle it with mozzarella cheese, then cook the whole thing in a convection oven for 15 minutes at 370°F.