When they have cooled down a little, peel them and then press them through the potato press.
As soon as the potatoes are only lukewarm, add the melted butter, egg, nutmeg and potato flour and knead carefully to a smooth dough on a work surface dusted with potato flour. Depending on the potato, a little more potato flour can be added - but it should not be too much, otherwise the dumplings will not become loose. Chill the potato dough for 1 day.
The next day, roll the dumplings to the desired size, dust them lightly with potato flour so that they do not stick to each other. (If the dumplings are not cooked immediately, they must be put back in the refrigerator.)
Now bring salted water to the boil in a large saucepan, reduce the temperature (the dumplings must not boil) and gradually slide the dumplings into the water and let them steep. Do not cook too many at once - the cooking water cools down too much.
When the dumplings float on the surface of the water (this can be the case after 8-10 minutes), turn off the stove and wait another minute, then pour off the water - done.