Blueberry Galette with Lemon Ice Cream

Name: Blueberry Galette with Lemon Ice Cream
Ingredients: 1 pt superpremium vanilla ice cream; 1 tablespoon finely grated fresh lemon zest; 1 1/2 tablespoons fresh lemon juice; 1 lb fresh blueberries (3 cups); 2 tablespoons cornstarch; 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 (from a 15-oz package); 1 tablespoon cold unsalted butter, cut into pieces; 1 large egg, lightly beaten; Garnish: grated lemon zest (optional)