Preheat oven to 400°F and line baking sheet with parchment paper.
Mix berries, sugar, cornstarch, lemon juice, and vanilla; let sit 10 mins.
Roll puff pastry to 10x12 inches; cut into rectangles and score a border.
If using, mix cream cheese, powdered sugar, and vanilla until smooth.
Spread cream cheese mixture inside the border of each pastry.
Spoon berry mixture over the cream layer.
Brush edges with egg wash and sprinkle sugar.
Bake 18–22 minutes until puffed and golden.
Cool 5–10 minutes on a rack before serving.