Knead the butter, quark, flour and a pinch of salt together and let the dough rest in the refrigerator for half an hour. Then roll out and cut into squares.
Fill each square with a spoon of jam and fold it into a triangle, pressing the edge down well. Brush the pockets with egg yolk and place on a baking sheet lined with baking paper. Bake at 200 ° C for about 20 minutes until the surface turns light brown. Dust with icing sugar and enjoy warm or cold.
You can also use this dough to make apple strudel or fill the dumplings with apple strudel filling.