Melt the butter in a small pot. Add milk and warm it up lukewarm. Mix flour, sugar and 1 pinch of salt. Knead the milk mixture, egg yolk, wine and grappa first with the dough hooks of the mixer, then with your hands to a smooth dough. Wrap the dough in foil and let it rest for about 30 minutes.
Roll out the dough very thinly on a little flour and make it a little larger with your hands (approx. 55 x 65 cm). Spread cranberries on one half of the dough in a total of 56 spots with enough space between them. Fold over the other half of the dough and press the edges well. Cut out rectangular doughnuts.
Heat the oil in a wide pot or in a deep fryer to approx. 180 °C. Fry the doughnuts for 6-7 minutes in portions until golden brown. Lift out with a skimmer and drain on kitchen paper. Dust with icing sugar and serve hot.