Cook the potatoes until they are done.
While the potatoes are cooking, dice the onions and toss them in a pan with a little oil (I used 2 tablespoons of rapeseed oil) - set aside.
Finely mash the cooked potatoes peeled, possibly with a potato press and leave to cool in a bowl.
Mix with the flour, yeast, salt and the egg yolk. Add linseed, butter and milk and "knead" into a smooth dough (my food processor does that) and then let the dough rise for about an hour.
Preheat the oven.
“Knead” the dough again and mix in the skipped onion.
Put the dough in a long form / roll and cut away parts with a knife and place them on the baking sheet and bake them brown at 170 degrees for about 30 - 35 minutes.
They taste best warm. But since I had 10 pieces, I packed 2 x 3 in bags and frozen ..... because I too want to enjoy Christmas in peace, not stand in the kitchen every day and "preparatory work" is half the battle 😉
Enjoy your meal