For the pie dough: In a stand mixer fitted with the paddle or using a handheld mixer, combine the flour and salt. Add the butter and beat at medium speed just until mixture resembles coarse meal, about 45 seconds.
At low speed, mix in the vinegar-water mixture, 1 tablespoon at a time, until the mixture just comes together. Turn the dough out onto a work surface and pat into a disk. Wrap in plastic and refrigerate for at least 4 hours or up to 2 days or freeze for one month.
Preheat the oven to 425°F. Liberally dust a work surface with flour. Using a lightly floured rolling pin, roll out the dough, rotating it a quarter turn every few rolls, until it’s ¼-inch thick. Roll the dough around the rolling pin and carefully unroll it into a 9-inch glass pie plate.
Pat the dough into the plate. Fold the overhanging dough under itself and press the dough to make it even. To crimp the dough, press the index finger of one hand between the index finger and thumb of another, allowing the crimp to extend past the edge of the pie plate a bit—this will prevent the rim of the dough from collapsing during baking. Place the pie dough in the freezer for at least 1 hour.
Scrunch up a sheet of parchment paper so it’s all wrinkled, then flatten it out and use it to line the pie dough. Fill with dried beans or pie weights. To parbake the crust, bake for 15 minutes, until the crust is light golden at the edges; rotate the pie plate halfway through baking. Remove the parchment and pie weights and let cool. To fully bake the crust, remove the parchment and pie weights, and continue to bake the crust for an additional 7 minutes, until lightly golden.
For the white chocolate cream: Preheat the oven to 275°F. Chop the white chocolate into small pieces and spread it evenly on a baking sheet lined with a Silpat or parchment paper. Once the chocolate melts in the oven for a few minutes, remove the baking sheet from the oven and stir the chocolate using a clean, dry rubber spatula.
Continue to cook the chocolate, stirring every 5 minutes, until the chocolate is golden brown, about 20 minutes total. This step can be done days in advance; keep the roasted chocolate at room temperature in a clean bowl.
In a small bowl, combine 1 ½ teaspoons of the chilled cream with the powdered gelatin. Allow to sit until the gelatin reconstitutes, about 5 minutes.
In a heavy bottomed saucepot, combine the milk and salt over moderately high heat. If the roasted white chocolate is not mostly melted, place it in a clean dry bowl over a pot of simmering water to melt, stirring often with a spatula. (It’s okay if it is a little bit chunky or pasty—the hot milk and blending will do the rest of the work, Fields says.) Once the milk mixture has reached a scald (bubbling at the edges), stir in the gelatin mixture, then remove from the heat.
In two additions, add the milk mixture to the melted white chocolate, stirring well with a spatula between each addition. The chocolate will want to take on that lumpy, seize-like quality again, but push ahead, it’ll work out, Fields advises. Once all of the milk has been added to the chocolate, blend with an immersion blender (or food processor) for about 45 seconds to a minute, until smooth.
Then, slowly pour in the remaining chilled cream while blending, until all incorporated. Let rest overnight in the fridge overnight before cooling.
For the filling: Preheat the oven to 375°F. In a large bowl, whisk together the pumpkin puree, eggs, brown sugar, salt, and spices until incorporated. Stir in the cream until well combined.
Pour the filling into the prepared pie shell and bake for about 1 hour, rotating halfway through baking, until the center is set. Remove from the oven and allow to cool completely.
Once the cream has set up and the pie has cooled, top the pie with the cream and serve. Pie can be loosely tented with foil and refrigerated for 4 days; bring to room temperature to serve.
