Pour yeast and sugar into milk. Beat eggs with butter. Combine these two mixes and mix well. Add flour. Knead the dough and place it in a warm place for 2 hours. Unroll the dough 1.5 cm thick and cut the donuts with two glasses of different diameters. Bake at 200 degrees for 20 minutes. Prepare the icing from a spoonful of milk, butter, icing sugar and dark chocolate. Dip the finished donuts with one side in the icing.