Combine flour, sugar, and salt in a food processor. Add cold butter and pulse until it resembles coarse crumbs.

Whisk together the egg, vinegar, and ice-cold water. Gradually pour this into the flour mix. Shape into a disc, wrap in plastic, and chill for 30 minutes.

Preheat oven to 375°F (190°C). Roll out chilled dough into a 9-inch pie plate, trim excess. Cover with parchment and fill with weights. Bake for 15 minutes.

Remove weights and parchment, continue baking until edges are golden.

In a large bowl, whisk canned pumpkin, sour cream, eggs, bourbon, vanilla extract, spices, salt, and maple syrup until smooth.

Add heavy cream if a thinner consistency is preferred.

Pour filling into pre-baked crust and bake at 350°F (175°C) for about 45 minutes.

Filling should be set with a slight jiggle in the center.

Allow pie to cool completely. Sprinkle sugar over the top and caramelize with a kitchen torch or broil in the oven for 1-2 minutes.

Slice and serve with whipped cream or vanilla ice cream.