Peel, wash and boil about 4½ lbs (osmushka)* potatoes until tender. Pour off the water and immediately mash the potatoes in the pan with a small wooden pestle until they are cool. Add salt and 1 full spoon butter and mix until they whiten. Stir in 1–1½ glasses milk, add 2–3 egg yolks or 1 egg, and mix again. Transfer to a sauté pan greased with butter, strew the top with rusk crumbs, and bake in a hot oven. Serve with roast meat, or better, for breakfast.