Steps
1. Preheat your oven to 400°F (200°C).
2. Roll out the puff pastry sheet on a floured surface to ensure it's even.
3. Cut the pastry into three equal rectangles.
4. Place the rectangles on a baking sheet lined with parchment paper and prick them with a fork.
5. Bake in the preheated oven for 15-20 minutes, or until golden brown and crispy.
6. Once baked, let the pastry cool completely.
7. Assemble the Mille-feuille by placing one rectangle on a plate, spreading a layer of dulce de leche, followed by a dollop of whipped cream.
8. Top with a second rectangle, repeat the layering, and finish with the third rectangle on top.
9. Dust with powdered sugar and garnish with fresh berries if desired.
10. Serve immediately and enjoy your delightful Dulce de Leche Mille-feuille!