Preheat the oven according to the puff pastry package instructions.

Roll out the puff pastry sheets and cut into triangles.

In a bowl, mix the blueberries, blackberries, raspberries, granulated sugar, and lemon juice.

In another bowl, whip the heavy whipping cream until soft peaks form.

In a separate bowl, blend the cream cheese, sour cream, powdered sugar, and vanilla extract until smooth.

Fold the whipped cream into the cream cheese mixture until well combined.

Place a spoonful of the berry mixture and a spoonful of the cream mixture onto each triangle of puff pastry.

Roll the triangles into croissants and brush with the beaten egg.

Bake in the preheated oven until golden brown, about 25 minutes.

Dust with powdered sugar before serving.