Shred the Striezel and put it in a bowl with 250 ml of milk.
Grease a baking dish. Preheat the oven to 180 °C.
Beat the egg whites with a pinch of salt until stiff. Beat 4 egg yolks with sugar and butter until foamy.
Stir in the curd, whipped cream and sour cream, then mix in the Striezel pieces that have been soaked in milk (if you like, you can stir in the raisins at this stage) and finally gently fold in the snow.
Roll out the strudel dough and place the mixture on top. Roll up tightly and fold over the ends. Place the strudel in the prepared form.
Mix the ingredients for the sauce. Pour over the strudel as it bakes.
Bake until golden brown. Sprinkle with powdered sugar before serving.