Preheat oven to 450 degrees, with rack in lowest position. On a lightly floured piece of parchment paper, roll each disk of dough to a 14-inch round. Transfer one round (still on paper) to a baking sheet for top crust; refrigerate.Advertisement
Line a 9-inch pie plate with remaining round of dough (do not stretch). Using kitchen shears, trim dough to a 1-inch overhang all around; refrigerate bottom crust.
In a large bowl, toss blueberries with sugar, cornstarch, lemon juice, and ginger; pour filling into bottom crust. Place chilled top crust over filling. Trim top crust to match bottom crust. Press edges of both crusts together, and fold overhang under itself; press to seal. Using thumb and forefinger, crimp edges. Cut a few slits in top of pie to let steam escape.
Place pie on a rimmed baking sheet. Bake 30 minutes; reduce heat to 375 degrees, and bake until crust is golden and juices are bubbling rapidly all over, 60 to 70 minutes more (if edges are browning too quickly, tent with aluminum foil). Transfer pie to a wire rack, and let cool to room temperature, at least 6 hours.