For the grammel dumplings for the filling finely chop the onion and lightly roast in a little butter. Finely chop the grams and mix with parsley, the roasted onion, garlic and marjoram. Season with salt and pepper.
Form small balls from the mixture and put them in a cold place. Cook the potatoes in the oven, let them steam out and press them through a potato press. Allow to cool.
On a floured work surface, knead potatoes with butter, egg yolks, salt and as much flour as the dough can hold until smooth.
Wrap in plastic wrap and chill in refrigerator for 15 minutes. Then form into a roll and cut slices. Wrap each grammel ball well with dough and shape into round dumplings.
Bring salted water to a boil and cook the grammel dumplings in it for about 7 minutes until lightly boiling. Lift out, drain and roll in hot butter crumbs.