Creating a delicious Napoleon Cake can be straightforward if you follow these simple steps:

1. Prepare the Puff Pastry: In a large bowl, combine the flour, salt, and sugar. Add the chilled butter and mix until the mixture resembles coarse crumbs.
2. Add Water: Gradually add cold water, mixing until the dough comes together. Be careful not to overwork it.
3. Chill the Dough: Divide the dough into four equal portions. Wrap each in plastic wrap and refrigerate for at least 30 minutes.
4. Roll Out Pastry: Preheat your oven to 400°F (200°C). Take one portion of dough and roll it out on a lightly floured surface to about 1/8-inch thickness. Cut it into a rectangle to fit your baking sheet.
5. Bake the Pastry: Place the rolled-out dough on a baking sheet lined with parchment paper. Prick it all over with a fork to prevent bubbling. Bake for 12-15 minutes or until golden brown. Repeat with the remaining portions of dough.
6. Prepare the Cream Filling: In a bowl, whip the heavy cream until soft peaks form. Gradually add powdered sugar and vanilla extract, continuing to whip until stiff peaks form. Add cornstarch and mix well.
7. Assemble the Cake: Once the pastry layers have cooled, place one layer on a serving platter. Spread a generous amount of cream filling on top, then add another layer of pastry. Repeat the process until all layers are assembled, finishing with a layer of cream on top.
8. Chill the Cake: Refrigerate the assembled cake for at least 1 hour to allow the layers to set and flavors to meld.
9. Optional Toppings: If you desire, drizzle chocolate ganache or spread fruit preserves between layers for added flavor.
10. Slice and Serve: Use a sharp knife to cut the cake into generous slices for serving.

These steps will guide you in creating this incredible dessert effortlessly.