Sift flour with sugar and vanilla sugar on a work surface.
Break up the butter and add it together with the egg yolks. Quickly knead all ingredients into a smooth dough and let stand covered in a cold place for about 1/2 hour. Roll out the dough on a floured work surface to a thickness of about 3 mm, cut out slices with a round cutter (approx.
3-4 cm in diameter) as desired and place on a baking tray lined with baking paper – keep dipping the cutter in flour.
For the snow mixture, beat the egg whites until stiff. Gradually add the sugar and whip the egg whites again until stiff. Spoon a little of this mixture onto each of the shortcrust pastry discs.
Bake in the preheated oven on the middle shelf at 175°C for about 15 minutes. Remove the cookies from the baking tray, let them cool completely and put two pieces together with warmed jam (alternatively, melted chocolate coating is also possible).