Preheat oven to 400°F
In a large pan over medium heat add apples, butter, brown sugar, cinnamon and lemon juice
Cook until soft and juices are released
Mix in cornstarch and stir gently until combined and thickened, then remove from heat
Cut puff pastry into 4.5x6 inch rectangles and place half of them on a baking sheet lined with parchment paper
Fill each pastry rectangle with 2-3 tablespoons of apple mixture
Cover with another puff pastry rectangle and press the sides down
Paint with egg wash
Bake for 25-30 minutes or until deep golden
Cover with cinnamon sugar before serving
