Chop the walnuts. Mix the flour, baking powder, salt, sugar, vanilla sugar and oatmeal together. Add the quark, eggs, butter in flakes and rum. Knead everything into a dough. Now knead the nuts and raisins into the dough. Place the dough on a floured work surface and cut in half. Shape each half into an approx. 70cm long strand. Twist both strands around each other like a cord. Place on a baking sheet lined with baking paper and shape into a wreath. Press both ends together. Bake in the oven preheated to 175 ° C for approx. 50 minutes.
Heat the jam and strain it through a sieve. Brush the still warm wreath with it and decorate with 1 tablespoon nuts and oat flakes each. Allow to cool and dust with powdered sugar before serving.