Preheat the Oven:
Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Prepare the Cream Cheese Filling:
In a mixing bowl, beat the softened cream cheese, sugar, and vanilla extract until smooth and creamy. Set aside.
Roll and Cut the Puff Pastry:
Lightly flour your work surface and unfold the puff pastry sheet. Roll it out slightly if needed to ensure even thickness. Cut the pastry into six equal rectangles or squares.
Assemble the Pastries:
Place a dollop of the cream cheese mixture in the center of each piece of puff pastry. Add a small handful of blueberries on top of the cream cheese.
Fold and Seal:
For turnovers, fold each piece of pastry diagonally to form a triangle. For open pastries, leave the filling exposed and gently fold the edges of the pastry up to create a border. Press the edges lightly with a fork to seal.
Apply the Egg Wash:
Brush the top and edges of the pastry with the beaten egg to ensure a golden, shiny crust.
Bake:
Transfer the pastries to the prepared baking sheet and bake for 18–22 minutes, or until the pastries are puffed and golden brown.
Cool and Dust:
Let the pastries cool on a wire rack for a few minutes. Dust with powdered sugar if desired.
Serve and Enjoy:
Serve warm or at room temperature. These are best enjoyed the same day but can be stored in an airtight container for up to 2 days.