In a large bowl, whisk together ¾ cup sugar and cornstarch; stir in blueberries, lemon juice, and almond extract.
On a lightly floured surface, roll half of dough into a 12-to 13-inch circle. Transfer to a 9-inch pie plate, pressing into bottom and up sides. Trim to ½-inch past edge of pie plate. Fill with blueberry mixture. Roll remaining dough into a 12-inch circle. Using a 2-inch diamond-shaped cutter, cut out design as desired. Place on top of filling. Trim dough to ½ inch past edge of pie plate. Fold edges under, and crimp as desired. Brush with egg, and sprinkle with 1 tablespoon sugar. Place pie plate on a rimmed baking sheet.
Bake for 10 to 15 minutes. Reduce oven temperature to 375° and bake until crust is golden brown and filling is bubbly, 45 minutes to 1 hour, covering with foil to prevent excess browning, if necessary. Let cool for 2 hours before serving. Store pie, covered, at room temperature for up to 2 days.
Beat cream and remaining 2 tablespoons sugar with a mixer at medium speed, slowly increasing to high speed, until soft peaks form, 2 to 3 minutes. Add buttermilk and beat until soft peaks form, about 1 minute. Serve with pie, if desired.
Buttermilk Pie Dough
In the work bowl of a food processor, pulse together flour, sugar, and salt. Add butter, and pulse until mixture is crumbly, about 1 minute. Add buttermilk, 1 tablespoon at a time, pulsing until a dough forms. Turn dough out onto a lightly floured surface and shape into 2 disks. Cover each tightly with plastic wrap; refrigerate until firm, about 2 hours.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/blueberry-pie/