Preheat your oven to 375°F (190°C). Cut the thawed puff pastry into squares and score a smaller square inside each one. Brush edges with egg wash, sprinkle granulated sugar on top, and bake for 15–18 minutes until golden brown and puffed. Allow to cool and create a well in the center.

In a saucepan, heat whole milk over medium until steaming. In a bowl, whisk together egg yolks, granulated sugar, cornstarch, and salt. Slowly add hot milk to yolk mixture while whisking. Return to saucepan and cook on low heat until thickened. Stir in vanilla extract and chill.

Once the custard is cool, fill each pastry shell with custard, leveling it off. Top with fresh berries for color and flavor.

Dust with powdered sugar and garnish with mint if desired. Serve immediately for the best texture.