2 cups all-purpose flour, 1/2 cup sugar, 1/4 teaspoon salt, 1/2 cup unsalted butter, chilled and diced, 4-6 tablespoons ice water
1 cup heavy cream, 1/4 cup powdered sugar, 1 tablespoon vanilla extract, 1/4 cup powdered sugar
To make the pastry: In a medium bowl, whisk together the flour, sugar, and salt. Add the butter and use your fingers to work it into the flour until it resembles coarse crumbs.
Gradually add the ice water, mixing until the dough just comes together. Form the dough into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.
Preheat oven to 375 degrees F (190 degrees C). On a lightly floured surface, roll out the dough to a thickness of about 1/8 inch. Cut out 4 (6-inch) circles.
Place the circles on a baking sheet lined with parchment paper. Bake for 12-15 minutes, or until golden brown. Let cool completely.
To make the filling: In a medium bowl, whip together the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
To assemble the cake: Place one pastry circle on a serving plate. Spread with about 1/4 cup of the filling.
Top with another pastry circle and repeat with the remaining filling and pastry circles. Dust the top of the cake with powdered sugar.
For a flaky pastry, be careful not to overwork the dough. If the dough is too dry, add a little more ice water. If the dough is too sticky, add a little more flour.
To prevent the pastry from shrinking, prick the bottom of the circles with a fork before baking. You can also use store-bought puff pastry for this recipe.
To make a chocolate Napoleon cake, simply spread a thin layer of chocolate ganache between the pastry layers.