First, we start the yeast. Crumble the yeast into a bowl, add part of the sugar and cover with lukewarm milk. Sift the semi-coarse flour into the mixing bowl, add the rest of the sugar, vanilla sugar, raisins (they can be soaked in rum), grated rind from half a lemon, and finally add salt. Cut the softened butter into cubes and add them together with the yolks to the dry ingredients in the mixing bowl. We turn on the kneader on the 1st or 2nd level (slow rotation) and add the risen yeast. Knead the dough until it is properly processed and does not stick to the bowl. Sprinkle the prepared dough with a little flour and cover with a towel, let the dough proof. We can use a convection oven, which we set to hot air mode, temperature to 38°C for 30 minutes. We divide the required number of small buns from the risen dough and roll them into long rolls and braid them. Transfer the braided Christmas cake to a baking sheet, brush with beaten egg, sprinkle with sliced almonds and leave to rise for another 10 minutes at the same setting as when the dough initially rose. Bake the Christmas challah prepared in this way in a preheated combi oven at 155°C, for combined operation with 20% steam, for 30 minutes.