Fresh Blueberry Galette

1 lb fresh blueberries (3 cups)
2 tablespoons cornstarch
1 tablespoon finely grated fresh lemon zest
1 tablespoon fresh lemon juice
1/4 teaspoon ground cinnamon
1/4 teaspoon salt
1/2 cup plus 1 teaspoon sugar
1 (9-inch) refrigerated pie dough
1 tablespoon cold unsalted butter, cut into pieces
1 large egg, lightly beaten

Put oven rack in middle position and preheat oven to 425°F. Line a large baking sheet with foil and butter foil.

Stir together blueberries, cornstarch, zest, juice, cinnamon, salt, and 1/2 cup sugar in a large bowl until combined.

Unwrap pie dough and unfold onto baking sheet, then spoon blueberry mixture onto center of dough, leaving a 1 1/2-inch border around edge.

Fold edge of dough over 1 inch of blueberry mixture, pleating dough, and then dot blueberry filling with butter pieces. Lightly brush pastry with some of beaten egg and sprinkle with remaining teaspoon sugar.

Bake until blueberry filling is bubbling and pastry is golden, 25 to 30 minutes. Cool slightly on baking sheet on a rack.

Super yummy served warm with scoop of lemon or vanilla ice cream.