Mix the butter and sugar, then fold in the egg yolks, curd cheese and sour cream. Beat egg whites into snow and fold in as well. Lay out puff pastry in puree (buttered) and fill with curd cheese mixture. Seal the side of the dough and brush with butter. Bake at 160 degrees for about 15 minutes.
In the meantime, bring the milk to the boil, mix the eggs and sugar and add to the cooled milk. Pour egg milk over the strudel and finish baking in 55 minutes.