• Thaw your puff pastry dough according to package directions.
• Preheat your oven to 400 degrees.
• Line a baking sheet with parchment or a silicone liner.

For the Blueberry Sauce:

• In a small sauce pan, combine the blueberries, sugar, cornstach, and water. Stir together carefully.
• Heat over medium heat for 2-3 minutes until bubbling nicely and thickened slightly.
• Remove the blueberry sauce from the heat and let it cool.

For the Turnovers:

• Cut the pastry dough into 4 squares per sheet.
• Put 1-2 TBS of filling in the middle of each square.

For the Egg wash:

• Whisk together the water and egg in a small bowl to create an egg wash.
• Brush egg wash over each edge of the pastry dough and fold in half to make a triangle. Press edges together with fingers.
• Pierce the top of each turnover with a fork or knife to let steam escape.
• Place on prepared baking sheet and repeat with remaining dough and filling.
• Brush remaining egg wash over the tops of turnovers.
• Bake for 15-20 minutes until golden brown.
• Allow to cool for about 20 minutes.

For the Glaze:

• Add the powdered sugar, milk, and vanilla extract to a small bowl and whisk them together until smooth. Add more powdered sugar or more milk as needed to get the right consistency.
• Drizzle the glaze over each turnover and serve.