For the Schlipfkrapfen dough, mix both types of flour with the egg, a pinch of salt and enough lukewarm water to make a pasta dough that is not too soft. Knead vigorously, form into a ball and let rest for 30 minutes covered with cling film.Meanwhile, for the filling, boil the potatoes until soft, peel while still hot and press through a sieve or grate on a grater. Finely chop the onions and sauté in a little butter until light. Stir into the potato mixture and add cheese, curd cheese, chopped chives, a pinch of nutmeg, a pinch of pepper and a pinch of salt. Form the pasta dough into a roll, cut off a piece and roll out into a 2-3 mm thin disc. Apply some filling, fold into crescent-shaped pouches and press the edge well. Depending on your skill, wave the edge between your fingers as you do so. In a large pot, bring salted water to a boil, place Schlipfkrapferl and cook in several tranches for about 10 minutes.
In the meantime, melt butter for the garnish. Lift out finished Schlipfkrapfen with a slotted spoon and arrange in deep preheated plates. Drizzle Schlipfkrapfen with melted butter and sprinkle with chives and grated cheese.