
Add the dough’s all-purpose flour, sugar, and salt into a food processor. Pulse to mix.
Cut the cold butter into tablespoon-size pieces and add to the food processor. Pulse until butter is cut into small pieces.
While pulsing, pour in the ice water slowly until a shaggy dough forms.
Knead the dough a few times, flatten into a disk, cover with plastic wrap, and chill in the fridge for an hour.
Combine all filling ingredients in a medium bowl and stir to combine.
Remove the dough from the fridge and rest for 5 minutes. Roll out to a circle about 1/4 inch thick.
Transfer dough to a parchment-lined baking sheet and fill with blueberry mixture, leaving a 3-inch border.
Fold the edges up and over the filling, creating pleats. Brush edges with egg wash and sprinkle with coarse sugar.
Bake at 425°F for about 25 minutes until golden brown. Cool for at least 30 minutes before serving.