Preheat the oven to 400°F. Line a baking sheet with parchment paper.

Unfold the thawed puff pastry sheets and roll them out slightly on a floured surface. Cut each sheet into 3 equal rectangles.

Place the rectangles on the prepared baking sheet, spacing them apart. Prick the surface of each rectangle with a fork to prevent puffing.

Bake for 15-20 minutes or until golden brown and puffed. Remove from the oven and let cool completely.

In a large bowl, whip the heavy cream with an electric mixer until soft peaks form. Gradually add the powdered sugar and vanilla extract, continuing to whip until stiff peaks form.

Once the puff pastry is cool, carefully slice each rectangle in half horizontally to create two layers.

On a serving platter, place one layer of puff pastry. Spread a layer of pastry cream over it, followed by a layer of whipped cream. Repeat with another layer of puff pastry, pastry cream, and whipped cream. Top with the final layer of puff pastry.

Spread a thin layer of whipped cream on top of the final pastry layer and garnish with fresh berries if desired.

Refrigerate the cake for at least 2 hours before serving to allow the layers to set.