Cut the rye bread and the pretzel into small cubes. Also cut the onion into cubes and season with half of the salt and pepper (this way the dumplings take on the heat) and sweat together with the bacon in the melted butter (1 tablespoon of the whole) until translucent.
Beat the eggs and sprinkle with the rest of the salt and pepper and whisk together. Put the bread / pretzel mixture in a deep bowl, slowly pour the lukewarm milk over it, and also add the eggs, onions and bacon to the bowl. Mix everything nicely with a wooden spoon. Now add the chives and nutmeg to the mixture and let the mixture steep for about 1 hour.
Brush a piece of aluminum foil (maximum as wide as the pot in which you want to cook the dumplings) with the remaining butter, spread the dough on the foil and roll it into a roll, twisting the ends together. Then take a large piece of plastic wrap and wrap it around the roll to make the roll waterproof.
Let the dumpling roll simmer for about 30 minutes. Let the mixture cool down briefly, remove it from the foil and cut into slices as thick as a thumb. If you want, you can briefly sear these slices in hot butter on both sides, I also like them with beef or venison.