- Heat oven to 375°F.
- Unwrap one layer of puff pastry and place on a piece of parchment paper that is on a baking sheet. Trim off corners (if you want).
- In a bowl, add sugar and cornstarch and sift together with a fork or whisk. Add in the blueberries and lemon juice and stir to coat.
- Pour blueberry mixture into the center of the puff pastry. Start folding the edges up and over the edge of the fruit. Do this around entire puff pastry.
- Crack an egg and beat it with a fork. Brush the puff pastry with the egg, covering it all.
- Sprinkle with the raw sugar.
- Bake for 15-25 minutes or until the pastry is a golden brown, not burnt.
- When done, remove from oven. and let the pastry sit for at least 10 minutes, allowing the sweet fruit juices to thicken slightly.
- Shave white chocolate over the top and serve. (If you want the white chocolate to be melted, add this right out of the oven.)