Instructions

1. Preheat the oven to 400°F (200°C).
2. On a lightly floured surface, roll out the puff pastry sheets until they're about 1/8 inch in thickness.
3. Cut the pastry sheets into equal-sized rectangles (around 3x6 inches each) and place them on a baking sheet lined with parchment paper.
4. Bake the pastry rectangles for 15-20 minutes, until they turn golden brown and puff up. Let them cool completely.
5. While the pastries are cooling, prepare the vanilla pastry cream. Heat the milk in a medium saucepan over medium heat until it's steaming but not boiling.
6. In a separate bowl, whisk together the sugar, egg yolks, and cornstarch until the mixture becomes smooth and well combined.
7. Slowly pour the hot milk into the egg mixture, whisking constantly to avoid scrambling the eggs.
8. Transfer the milk and egg mixture back to the saucepan and cook over medium heat, stirring constantly until the mixture thickens into a custard-like consistency.
9. Remove the saucepan from the heat and stir in the vanilla extract. Let the pastry cream cool completely.
10. To assemble the Napoleon, place a puff pastry layer on a serving plate. Spread a layer of the cooled vanilla pastry cream on top, and then add another layer of pastry. Continue this process until all the pastry and cream are used up, ending with a pastry layer on top.
11. Chill the assembled Napoleon in the refrigerator for at least 2 hours to let the flavors meld together.
12. Before serving, dust the top layer of puff pastry with powdered sugar for a beautiful, professional finish. Slice the Napoleon into individual servings and serve chilled.