Chocolate doughnuts

Mix the flour with yeast dissolved in warm milk, sugar, egg yolks and salt. It is good to mix with a wooden spoon until air bubbles appear. Then add egg whites whipped into strong foam to the dough and put it in a warm place for 30 minutes. Roll the dough that has come up on a floured board into a layer 1 cm thick. Cut round cakes from it with a glass and put it again for 30 minutes in a warm place. Fry the doughnuts in large quantities of badly warmed fat until ruddy. Sprinkle ready-made doughnuts with icing sugar or a mixture of grated chocolate and icing sugar.