Wash, halve and stone the plums. Cut the plum halves into thin slices. Preheat the oven to 200 ° C. Line a baking sheet with parchment paper. Cut the puff pastry into 10 - 12 strips approx. 2 cm wide and approx. 20 cm long.
Place the plum slices lengthways next to each other, slightly overlapping, on the puff pastry strips, leaving approx. 1 cm free at the ends. Sprinkle the plums with vanilla sugar. Whisk the egg yolk and brush the ends of the dough with it. Carefully roll up the dough with the plums and press the ends firmly.
Brush the puff pastry roses all around with the rest of the egg yolk and place on the baking sheet. Bake in the oven (center) for approx. 15 minutes until golden brown. Dust with icing sugar and best serve warm.