For the donuts, dissolve the yeast in the warm milk. Beat all the ingredients in a mixing bowl with the dough hook until a smooth dough comes off the sides of the bowl.
Cover and let rise in a warm place until doubled in size. Knead together on a floured work surface and roll out to 1- 1.2 cm thick and cut out with a round shape about 4 cm.
Cut out a small hole in the center, cover and let rise again. Heat the oil in a deep fryer to 175 °C and fry the rings until light brown.
When cooled, coat with chocolate coating