For the Bohemian puff pastry with vanilla sauce, knead the flour, egg, egg yolk, butter, a little cold milk and a pinch of salt until smooth, wrap the dough in aluminum foil and let it rest in a cool place for 1 hour. On a floured work surface, roll out the dough as thinly as possible and cut into regular lozenges or squares about 3 to 4 cm on a side.
Heat the clarified butter strongly and fry the puff pastries, which have been well removed from the flour, gradually in several batches until they are golden on both sides and puffed up. If the excess flour makes the fat too brown, replace it in between. Lift out the puff pastry, drain well or dab with paper towel, sprinkle with powdered sugar and serve hot with the vanilla sauce prepared in the meantime.
For the custard, stir a third of the milk with vanilla sugar and custard powder until smooth, boil the remaining milk with the granulated sugar, stir in the custard mixture and bring to the boil again briefly. Remove the saucepan from the heat and whisk in the egg yolks and whipped cream quickly.
Rinse the pudding molds briefly with cold water, drain and pour in the custard and serve while still lukewarm.Before eating, briefly dip the crispy Bohemian Polsterzipf in the custard while it is still warm.