Slowly melt the butter in a saucepan. Crumble and melt the yeast (I always use fresh yeast). Mix the flour, sugar, vanilla sugar, eggs and milk in a mixing bowl with a hand mixer and mix with the butter and yeast mixture to form a homogeneous dough.
Fold in 2-4 tablespoons of chocolate drops or raisins (amount depending on taste) and let rest covered for at least 30 minutes.
Preheat the oven to 220 degrees.
Dust the work surface with a little flour and shape the dough into a roll. Cut off even pieces and shape them into rolls. Place these on a baking sheet lined with baking paper. Keep your distance, because the rolls are still rising. Bake on the middle rack for 10-12 minutes.