Step 1
Preheat the oven to 350 degrees F and line two large baking sheets with parchment paper.
Step 2
Stir one of the raspberry packages together with the sugar and 2 tablespoons apple juice in a medium saucepan over medium heat. Reserve the second container of raspberries.
Step 3
Cook the raspberries for about 5 minutes until the sugar is dissolved into the juice the raspberries start to soften and the juice comes to a simmer.
Step 4
Whisk the remaining tablespoon of apple juice with the cornstarch and add to the simmering raspberries. Cook for 1-2 minutes more then stir in the remaining fresh raspberries.
Step 5
Unfold the thawed puff pastry sheets and cut each sheet into 4 squares.
Step 6
Brush the edges of each square with the egg wash and spoon the raspberry filling into the center of each square.
Step 7
Lift one corner of each square and carefully fold diagonally to make triangle-shaped puff pastry packets pressing gently to seal the pastry edges.
Step 8
Transfer the turnovers to the prepared baking sheets. Brush egg wash on each turnover and sprinkle with raw sugar if desired.
Step 9
Bake for about 20 minutes until the pastries are puffed and golden brown. Cool on the baking sheets for 5 minutes before serving.