Preheat the oven to 375 degrees. Spray non-stick cooking spray directly onto the bottom of two baking sheets. Set aside. Then, wash and dry the produce. Core, peel, and dice the apples.
In a medium saucepan, combine the apples, sugar, butter, cornstarch, cinnamon, nutmeg, and salt. Stir to combine. Cook for about 5-7 minutes or until the apple mixture begins to thicken. Set aside and allow to cool.
While the apple mixture cooks, unfold the puff pastry onto a lightly floured surface. Use a rolling pin, gently roll each puff pastry sheet slightly larger in size, about 20 percent in both widths and lengths. Place each rolled out puff pastry sheet on its own prepared baking sheet.
Next, using a slotted spoon, spoon half of the cooled apple mixture over the middle third of one of puff pastry sheets. Using a sharp knife, cut slits in the puff pastry dough, about 1-inch apart lengthwise down each side of the apple filling. Approximately 13-16 strips should be cut on both sides. Crisscross the strips over the apple filling and continue to crisscross down the apple strudel.
Repeat step 4 with the second puff pastry sheet.
Using a pastry brush, brush both apple strudels with beaten egg. Then, bake the strudels in the oven for 30-35 minutes or until puffy and golden brown.
While the apple strudel bakes, prepare the vanilla glaze. In a medium bowl, whisk together melted butter, vanilla extract, milk, salt, and powdered sugar. For a thicker glaze, add more powdered sugar. For a thinner glaze, add more milk to thin it.
When the apple strudel has slightly cooled, drizzle the vanilla glaze on top. Slice and serve. Enjoy!
Make one larger apple strudel and skip the criss-cross pattern. Roll both sheets of puff pastry out to make them larger. Place all of the apple mixture on one puff pastry sheet, and use it as the bottom. Place the second puff pastry sheet on top. Using a fork, crimp the sides to seal the edges and cut slits in the surface. Brush with a beaten egg.