How to Make It
Preheat oven to 425°F. Roll pastry dough into a 12-inch circle on a lightly floured surface. Fit dough into a 9-inch pie plate; trim excess dough, and crimp edges. Chill pie shell, uncovered, until firm, at least 30 minutes. (Pie shell can be chilled 8 hours or overnight).
Line chilled pie shell with parchment paper, and fill with pie weights. Bake in preheated oven until edges are lightly browned, about 15 minutes. Remove parchment paper and pie weights; prick bottom of pie shell several times with a fork. Return to oven; bake at 425°F until bottom is lightly browned, 4 to 6 minutes. Transfer to a wire rack, and let cool completely, about 30 minutes. Reduce oven temperature to 350°F.
While pie shell cools, whisk together 3/4 cup boiling water, molasses, 1 tablespoon orange zest, and baking soda in a large bowl. Let cool 20 minutes.
While molasses mixture cools, combine flour, brown sugar, and salt in bowl of a food processor. Pulse to combine, about 8 times. Add cold butter, and pulse until mixture is thoroughly combined and sandy, about 8 times. Stir 1 cup flour mixture into molasses mixture.
Pour molasses mixture into cooled pie shell. Sprinkle remaining flour mixture evenly over top of pie all the way to the crust. Bake at 350°F until filling is just set, 40 to 45 minutes, shielding edges of pie with aluminum foil after 10 minutes if needed to prevent excess browning. Transfer pie to a wire rack, and let cool completely, about 3 hours.
Just before serving, combine heavy cream, granulated sugar, vanilla bean seeds, bourbon, and remaining 1 tablespoon orange zest in bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until soft peaks form, about 1 minute. Serve pie with whipped cream.