Peel the apples and cut them into cubes. In a bowl, combine the apples, walnuts, raisins, sugar and cinnamon and mix well. Once the puff pastry loosens up, take one sheet, coat the edges with the egg whites.
In the middle, put half of the mixture and roll it up. Spread the top with egg yolk. Repeat with the other sheets of puff pastry. Bake in a preheated 428°F (220 °C) oven, then reduce to 392°F (200 °C) for about 40-50 minutes.
Sprinkle the baked strudel with powdered sugar.