In a food processor, combine all-purpose flour, granulated sugar, and salt. Pulse until mixed. In a separate bowl, whisk together egg, white vinegar, and ice water. Add cold, cubed butter to the flour mixture and pulse until coarse crumbs form. Drizzle in the egg mixture and pulse until dough just holds together. Wrap in plastic and chill for 30 minutes.

Preheat your oven to 375°F (190°C). On a lightly floured surface, roll out the chilled dough to fit a 9-inch pie plate. Gently transfer the rolled dough into the plate, crimping the edges to create a decorative border. Place parchment paper over the crust, fill with pie weights, and pre-bake for 15 minutes. Remove weights and let the crust cool slightly.

In a large bowl, whisk together eggs, pure canned pumpkin, sour cream, bourbon, vanilla extract, and the spices. In a saucepan, heat pure maple syrup until it simmers, then whisk in heavy cream. Combine this mixture with the pumpkin blend until smooth and well incorporated.

Pour the rich filling into the pre-baked crust and smooth the top with a spatula. Bake at 350°F (175°C) for 55-60 minutes, or until the center is set but still has a slight jiggle.

When ready to serve, sprinkle an even layer of granulated sugar over the top of the cooled pie. Use a kitchen torch to caramelize the sugar until bubbly and golden brown. Let it rest for a few minutes before slicing and serving.