Preheat the oven to 400°F (200°C). Line a large baking sheet with parchment paper. Make sure the puff pastry is thawed but still cool to the touch.

In a medium mixing bowl, combine the softened cream cheese, powdered sugar, and vanilla extract. Mix until smooth and creamy, with no visible lumps.

Wash the berries and pat them dry with paper towels. Remove the stems from the strawberries and cut them into small pieces. Leave the blueberries and small raspberries whole.

Unfold the puff pastry sheets on a lightly floured surface and gently roll them out to smooth any creases. Cut each sheet into 9 equal squares, making 18 squares in total.

Place approximately 1 teaspoon of the cream cheese filling in the center of each pastry square. Add a few berries on top, taking care not to overfill.

Bring the four corners of each pastry square together over the filling and pinch the edges firmly to seal. Gently shape each pastry into a small ball or rounded bundle.

Arrange the filled pastries seam-side down on the prepared baking sheet. Brush the tops lightly with the beaten egg and sprinkle with granulated sugar, if desired.

Bake for 15–18 minutes, or until the pastries are puffed, golden brown, and crisp.

Remove from the oven and allow the pastries to cool on the baking sheet for about 5 minutes. Dust with additional powdered sugar, if desired, and serve warm.