Preheat the oven at 200 degrees Celsius, using the hot air program.
Mix the butter, vanilla sugar, cinnamon powder, and the sugar in a bowl.
Roll out the puff pastry dough, and spread evenly the filling all over.
Roll it from the long side ion to a big roll.
Cut in slices and place in small paper or silicon baking forms.
Whip the egg and brush each bun.
Sprinkle some decorating sugar on top.
Place on a baking sheet and place in the middle of the oven for approx. 20 minutes.
Take out the buns and let them cool down for a few minutes.