Wash the potatoes thoroughly, peel them, and boil them.
Mash the boiled potatoes and mix well with salt, sugar, and butter.
Add flour, milk, and yeast to make a dough.
Let the dough rise for about 1 hour.
Divide the dough into small pieces, fill with the potato filling, and shape into balls.
Brush the tops with egg wash.
Bake in a 180°C oven for 20 minutes.