Preheat oven to 375 degrees. Line a baking sheet with parchment paper.
Peel, core, and chop apples into 1/2" cubes. You will need 2 cups of chopped apples. Place them in a bowl and add cinnamon, 2 tablespoons sugar, and flour. Set aside.
In another bowl combine finely chopped walnuts, raisins, brown sugar, 2 tablespoons sugar, and bread crumbs. Set aside.
Lightly flour a flat surface. Roll out one sheet of puff pastry into a 10 x12-inch rectangle. Spread 1/2 of nut mixture in a line, along the longest end of the pastry, leaving a 2-inch border. Place 1/2 of the apples on top of the nut mixture. Starting at the 2-inch border, gently lift the pastry over the apple filling and start rolling into a log. Pinch the ends and tuck under. Transfer to the baking sheet, seam side down. Repeat with remaining puff pastry sheet using the same method.
In a small bowl, combine the egg with water and brush the tops with egg wash. Make slits at an angle on top to allow the steam to escape.
Bake for 30 to 35 minutes until the crust gets nicely golden brown. Cool slightly and dust with confectioner's sugar if desired. Serve warm with vanilla ice cream.