The pumpkin pie is old-school. The toasted marshmallow fluff, decidedly retro. Put them together, though, and you’ve got a modern, sophisticated Thanksgiving dessert that also happens to be a smooth, creamy, spicy, gooey grand finale.
Brown butter: In a small saucepan, melt 2 sticks unsalted butter over medium-low heat. Cook until the milk solids separate out and turn golden brown and fragrant like toasted nuts, 10 minutes. Refrigerate until solid, 15 minutes. You will end up with half the amount of brown butter. Meanwhile, pulse the graham crackers to fine crumbs in a food processor. Place in a bowl and set aside.
Crust: Add the brown butter to the bowl of a stand mixer fitted with the paddle attachment. Mix on low speed to break up, 30 seconds, then add the brown sugar and continue mixing on medium speed until aerated, 2 minutes. Scrape the sides and bottom of the bowl to bring the batter together. Crack the egg into a small cup or bowl with the vanilla and, with the mixer on medium speed, add to the batter to combine almost completely. Turn mixer off and scrape the sides and bottom of the bowl with a rubber spatula to bring the batter together. Mix on medium speed until nearly homogeneous, 20—30 seconds. Add both flours, salt, and graham cracker crumbs all at once and mix on low speed until the dough just comes together but still looks shaggy, about 30 seconds. Do not overmix. Remove the bowl from the stand mixer. With a plastic bench scraper, bring the dough together completely. Stretch a sheet of plastic wrap on a work surface and wrap dough into a rectangle. Refrigerate until chilled throughout, 1 hour or up to overnight.
Bring dough to room temperature, 10 minutes. Spray pie tin with nonstick spray. Press pieces of dough into the bottom and up the sides of the pie tin, cleaning off edge of excess dough. Press plastic wrap on top of dough to make sure it's even and no thicker than ¼-inch. Chill dough while making pumpkin filling.
Filling: Preheat oven to 400 degrees F. In a bowl, whisk eggs, vanilla, sugar, pumpkin, ginger, cloves, cinnamon, salt, molasses, evaporated milk, and bourbon. Pour into the chilled pie crust (you may have some custard left over, depending on the size of your pie tin). Place on baking sheet and bake 15 mins, then turn oven down to 325 degrees F and bake approximately 40 minutes more, until custard is set. Let cool while you make the marshmallow fluff.
Marshmallow fluff: In a medium saucepan, cook sugar, water, and corn syrup on high heat until the temperature reaches 238 degrees F. Meanwhile, in a stand mixer, whip egg whites, salt, and cream of tartar on medium until stiff peaks form. When sugar is at 238 degrees F, turn mixer to low, and slowly add sugar to egg whites. Increase speed to high and whip until the mixture is cool, aerated, and super thick. "Fluff" it on top of the cooled pie, using two spoons to form peaks.
Assembly: Using a kitchen blowtorch, toast the marshmallow topping until it's tan and toasty, 20—30 seconds. (If you don’t have a blowtorch, stick it under the broiler.) Serve.