Half of the softened butter mix of foam and gradually added yolks. Egg whites are broken down into the snow, add sugar and beat continues until the hard snow. Mix with treated yolks, add the flour and carefully pour in a bowl of milk boiled with the rest of butter and vanilla. Bake in a hot oven (6-8 minutes) removed, chopped into pieces, which are arranged in a dish and sprinkle with vanilla sugar.