Preheat your oven to 400°F (200°C) and prepare a baking sheet with parchment paper.

Roll out thawed puff pastry sheets on a lightly floured surface to about 1/8 inch thick and transfer to the prepared baking sheet.

In a medium saucepan over medium heat, combine the milk, sugar, and vanilla extract, stirring until warm.

Whisk egg yolks and cornstarch together in a separate bowl, then slowly add the warm milk mixture while whisking to avoid curdling.

Return the mixture to the saucepan and cook over medium heat, stirring continuously until thickened, about 5-7 minutes.

Pour the thickened custard into the center of the rolled puff pastry and spread evenly, folding pastry edges over the custard.

Bake in the preheated oven for 25-30 minutes until golden brown.

Remove from oven, let cool for 10 minutes, then transfer to a wire rack to cool completely before dusting with powdered sugar.

Top with fresh berries before serving.