Heat up a pan with the butter and cook the chopped onion until translucent and soft.
Grab a large mixing bowl and add in the sautéed chopped onion, bread pieces, milk, egg, all purpose flour, salt, black pepper, nutmeg and parsley.
Mix everything together and mash together with your hands until all ingredients are well incorporated.
Leave the bread dumpling mass to rest for about 15 minutes.
Prepare a large pot with water and salt and bring to a boil.
Shape your dumplings into equal sized balls.
Drop the semmelknödel dumplings into the cooking water. Reduce the heat of the water so that the water won't boil up too much or else the movement can open up the dumplings. The water should be cooking but not vigorously.
Cook the dumplings for about 8-10 minutes. They will swim on top.
Take out the knödel from the cooking water and strain.
Serve still hot as a side dish with other local meals.