How to make
Defrost the dough in advance, but it should still be very cold. Roll it out slightly and cut it into equal sized rectangles.
Place the plum jam on half of the rectangles. Homemade whole fruit jam is preferable.
Separate the yolk from the white of one egg. With the egg white, coat the edges of the rectangles with the stuffing.
Cover with another rectangle of puff pastry and lightly press the edges to stick both of them together. Make slits on top of the puff pastries.
Brush them with beaten egg yolk and sprinkle them with powdered sugar. Bake in a preheated oven at 360°F (180°C), until the dough rises and the crust caramelizes.