How to Make It
Prepare Crust: Process first 4 ingredients in a food processor until mixture resembles coarse meal. With processor running, gradually add 4 Tbsp. ice-cold water, 1 Tbsp. at a time, and process until dough forms a ball and pulls away from sides of bowl, adding up to 2 Tbsp. more water, 1 Tbsp. at a time, if necessary. Divide dough in half, and flatten each half into a disk. Wrap each disk in plastic wrap, and chill 2 hours to 2 days.
Prepare Filling: Place 1 cup blueberries in a large bowl; crush blueberries with a wooden spoon. Stir cornstarch and vinegar into crushed berries until cornstarch dissolves. Stir sugar, next 5 ingredients, and remaining 6 cups blueberries into crushed berry mixture.
Unwrap 1 dough disk, and place on a lightly floured surface. Sprinkle with flour. Roll dough to 1/8-inch thickness. Fit dough into a greased (with butter) 9-inch deep-dish pie plate. Repeat rolling procedure with remaining dough disk; cut dough into 12 to 14 (1/2-inch-wide) strips. (You will have dough left over.)
Pour blueberry mixture into piecrust, and dot with butter cubes. Arrange piecrust strips in a lattice design over filling. Trim excess dough.
Reroll remaining dough, and cut into 6 (9- x 1/2-inch) strips. Twist together 2 strips at a time. Whisk together egg and 1 Tbsp. water. Brush a small amount of egg mixture around edge of pie. Arrange twisted strips around edge of pie, pressing lightly to adhere. Brush entire pie with remaining egg mixture. Freeze 20 minutes or until dough is firm.
Preheat oven to 425°. Bake pie on an aluminum foil-lined baking sheet 20 minutes. Reduce oven temperature to 375°, and bake 20 more minutes. Cover pie with aluminum foil to prevent excessive browning, and bake 25 to 30 more minutes (65 to 70 minutes total) or until crust is golden and filling bubbles in center. Remove from baking sheet to a wire rack; cool 1 hour before serving.