In the bowl of your stand mixer, combine water, all-purpose flour, sugar, salt, baking powder, fresh yeast, and salted butter.
Using the hook attachment, mix on slow for 5 minutes to bring the dough together.
After 5 minutes, increase the speed to medium-fast and let the dough mix for 15 minutes.
Flatten into a thin, long rectangle and wrap tightly in plastic wrap. Chill the dough in the refrigerator until they are completely cold, at least 1 hours.
Filling
Mix softened butter, sugar, cinnamon, vanilla sugar, and salt until smooth.
Buns
Roll out the chilled dough into a thin, long rectangle. Have the short side facing you.
Spread the filling evenly over the rolled-out dough.
Sprinkle on the raisins.
Roll up the dough tightly, creating a log.
Cut the log into 60g slices and place them on a tray lined with parchment paper.
Proof, covered in plastic, for 30 minutes.
While proofing, boil the brown sugar and water together to make simple syrup.
Once the buns are looking fluffy, pillowy and proofed, bake them in a 200C/400F oven for 8-10 minutes or until golden brown.
As soon as they are out of the oven brush with the brown sugar syrup.
Let cool before enjoying.
Notes
If using dry yeast, use 17g. If you don't have vanilla sugar substitute 1:1 with vanilla extract.