Mix the yeast with a little sugar, half of the lukewarm milk and a little flour to a thick steam. Dust with flour and let rise in a warm place.
Mix the remaining milk, sugar, melted butter, yolks, egg, salt, vanilla sugar and lemon zest until lukewarm.
When the dampfl has doubled in volume, beat all ingredients until smooth. Let it rise in a warm place.
For the filling, boil all the ingredients except the nuts. Then stir in the nuts and cook briefly. Let the nut filling cool a bit and spread it on the dough.
Roll out the dough into a rectangle on a floured work surface and spread with the prepared nut filling.
Now roll it up from both sides to the center and place it in a buttered and sugar sprinkled loaf pan.
Leave to rise, brush with melted butter if desired and bake in a preheated oven at 175°C for about 1 hour.