In a food processor, pulse together all-purpose flour, granulated sugar, and salt until well combined. Add cold, cubed unsalted butter and pulse until the mixture resembles coarse crumbs. In a separate bowl, mix an egg with vinegar and ice water before adding it to the flour mixture. Form the dough into a disc, wrap in plastic, and refrigerate for 30 minutes to firm up.

Once chilled, roll out the crust on a floured surface to approximately 1/8 inch thick. Gently transfer the dough to a pie plate, trimming any excess at the edges. Line the crust with parchment paper and fill with pie weights. Bake at 375°F for 15 minutes until the edges are lightly golden. Remove the weights, brush the crust with beaten egg white, and return to the oven for an additional 5 minutes.

In a large mixing bowl, whisk together eggs, canned pumpkin, sour cream, bourbon, vanilla extract, and warm spices until smooth and well blended. In a small saucepan, gently heat maple syrup until warm, then slowly whisk in the heavy cream. Combine the syrup mixture with the pumpkin mixture, stirring until fully incorporated and creamy.

Pour the luscious pumpkin filling into the pre-baked crust, smoothing the top to create an even layer. Bake the pie at 350°F for 55-60 minutes, or until the filling is set but still slightly jiggly in the center.

Allow the pie to cool completely at room temperature on a wire rack for about an hour. For best results, refrigerate the pie overnight to let the flavors meld. Just before serving, sprinkle an even layer of granulated sugar on top and use a kitchen torch to caramelize the sugar until it’s golden brown and crackling.