For the Weinbeerlstrudel, soak the grapes in ice wine overnight. Separate the egg, add the yolk to the curd cheese in a bowl. Add the custard powder and the sweetener (you can of course also use sugar to taste).
Stir everything thoroughly, then mix in the soaked grapes. Roll out the puff pastry and spread the filling on it, leaving a margin of about 3 cm all around.
Brush this edge with the egg white, form a roll and press the edges well together. Place the roll on a piece of baking paper and put it in a large loaf pan so that the strudel does not spread.
Place the loaf pan on the second lowest shelf in the preheated oven and bake at 170 degrees top/bottom heat for about 35 to 40 minutes.