In a food processor, combine all-purpose flour, granulated sugar, and salt until blended. Mix egg, white vinegar, and ice-cold water in a separate bowl. Gradually add this liquid to the flour mixture until a dough forms. Chill the dough for 30 minutes in the refrigerator, then roll it out into a 12-inch circle. Fit the dough into a 9-inch pie plate, and pre-bake the crust at 375°F for 15 minutes. Brush with egg white for shine.

In a large mixing bowl, whisk together the eggs, pure canned pumpkin, sour cream, bourbon, vanilla extract, and the ground spices (cinnamon, ginger, nutmeg, cardamom, and allspice). Stir until the mixture is smooth and well-combined. In a small saucepan, gently heat pure maple syrup until it simmers, then fold it into the pumpkin filling.

Pour the creamy pumpkin filling into the pre-prepared crust, spreading it evenly. Place the pie in an oven preheated to 350°F and bake for 55-60 minutes. Watch for the filling to be slightly jiggly in the center when done. Once baked, remove the pie from the oven and let it cool completely on a wire rack.

Once cooled, cover the Bourbon Pumpkin Pie with plastic wrap and refrigerate it overnight.

When ready to serve, evenly sprinkle granulated sugar over the top of the chilled pie. Using a kitchen torch, carefully caramelize the sugar until it forms a golden, crackly layer.