Sift the flour into a large bowl. Make a well in the middle. Crumble the yeast in the well, add 100 ml of lukewarm milk and a tablespoon of sugar. Let it sit for 15 minutes until a starter develops. Whisk the egg yolks with the remaining milk and add it to the bowl together with the softened butter, remaining sugar, vanilla sugar, two tablespoons of rum, mace and lemon zest. Using a wooden spoon, work a soft dough, cover it with a clean dish cloth and let it rise in a warm place for an hour.
In the meantime, preheat the oven to 350°F. Soak the raisins in the remaining rum (my grandma would do that :-). Add the raisins, almonds and candied fruit to the dough and let it rise for another hour. It will double in size.
Roll the dough with a pin and fold it lengthwise to achieve the stollen shape. If using marzipan, place it in the middle of the dough before folding.
Transfer the stollen onto a greased cookie sheet (or a silicone baking mat) and let it rise for a few more minutes.
Bake for 50- 60 minutes. If it browns too quickly, cover it with aluminum foil.
Brush the hot stollen with butter and cover generously with powdered sugar. When the stollen cools down and the sugar soaks in, give it another sprinkle of sugar.