Step 1

Preheat oven to 425 degrees F. Line a baking sheet with parchment paper. Unfold puff pastry onto a cutting board and cut into 4 equal squares.

Step 2

In a skillet over medium heat, melt butter. Stir in apples, 1/4 cup sugar, cinnamon, and cornstarch and cook 3 to 4 minutes, or until tender.

Step 3

Spoon about 2 tablespoons of apple mixture into center of each puff pastry square, leaving 1/2-inch border around edges.

Step 4

In a small bowl, whisk together egg white and water. Brush edges of each square with mixture. Fold each square into a triangle. Using a fork, press edges to seal. Brush top of each puff pastry with remaining egg white mixture and sprinkle with remaining sugar. Place turnovers on prepared baking sheet.

Step 5

Bake 12 to 14 minutes, or until golden brown.