Instructions

1. Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
2. In a mixing bowl, gently combine the blackberries, 1/4 cup of granulated sugar, cornstarch, and lemon juice. Mix until the blackberries are well-coated, then set aside to allow the flavors to meld.
3. Roll out the thawed puff pastry on a lightly floured surface and cut it into 6 equal squares, approximately 5x5 inches each.
4. Spoon a generous amount of the blackberry mixture into the center of each pastry square, being careful not to overfill to avoid spilling during baking.
5. Fold each pastry square over to form a triangle. Press the edges firmly to seal, and use a fork to crimp the edges for a decorative finish.
6. Brush the tops of the turnovers with the beaten egg to achieve a beautiful golden color while baking.
7. Carefully place the turnovers on the prepared baking sheet, ensuring they are spaced apart for even baking.
8. Bake in the preheated oven for 20-25 minutes, or until the pastries are puffed and golden brown.
9. Remove from the oven and let them cool for a few minutes on a wire rack.
10. Dust each turnover with powdered sugar before serving for an elegant touch.