Preheat the oven to 375 F.
Peel, core and chop the apples to about ½ inch cubes. Place them in a bowl and add the cinnamon, sugar, and flour. Give it a good mix and keep it aside for about 30 mins so that all the flavors can come together.
In another bowl combine all the ingredients for the nut layer and keep aside. I instead of chopping the nuts gave it a pulse in the mixer.
Thaw the pastry sheet to room temperature and roll it out on a well floured surface to about 12 x 14 inches.
Sprinkle the nut layer on the sheet covering one half of the sheet vertically. Be sure to leave about an inch on the sides.
Then layer it with the prepared apple mixture.
Life up one side of the pastry sheet and start rolling it into a log. Lay it on the baking sheet lined with parchment paper seam side down. Make sure to pinch the ends and tuck them under the log.
Brush the top with egg wash. (Break open one egg and add about a teaspoon of water. Mix well and the egg wash is ready). Look below for substitutions instead of egg wash.
Make several slices on top with a sharp knife for all the steam to escape. (This is very important if you do not want an explosion inside your oven).
Put it in the oven and let it bake for about 40 to 45 mins or until golden brown.
Cool it slightly on a wire rack.
Serve the Apple Strudel warm with a dollop of vanilla ice cream or with whipped cream.