Steam the finely diced onion in butter or clarified butter until translucent, set aside and allow to cool.
In the meantime, stir the sausage meat with the milk until smooth. Add egg, breadcrumbs, chopped parsley, nutmeg and the sautéed onions and stir well. Using a spaetzle slicer, slice portions into boiling meat broth or lightly salted, boiling water and let it steep for about 5 minutes over a low heat.
I always first shave the fried noodles in salted water and only then add them (drained well) to the meat broth, otherwise it will be a little cloudy.
The drained fried noodles can be frozen well in portions, so that you always have a soup to hand.