Boris Portnoy's Pumpkin Pie

1. 1
   Heat the oven to 200°F and arrange a rack in the middle.
2. 2
   Completely wrap the pumpkin in foil, place it on a baking sheet, and bake until very soft, 6 to 8 hours.
3. 3
   When cool enough to handle, remove the foil and break the pumpkin open with your hands. Using a spoon, scoop the flesh into a large bowl, discarding the seeds and skin. Place the pumpkin flesh in a food processor and process until smooth, about 2 minutes. (Alternatively, you can use a stick blender to process the pumpkin.) You will need 2 cups of purée. Store in a sealed container in the refrigerator until ready to use.

For the pie crust:

1. 1
   Place the butter and sugar in a stand mixer fitted with a paddle attachment and mix on medium-high speed until pale in color and fluffy, about 3 minutes. Add the egg and mix until incorporated. Turn the mixer off and add the flour, cornstarch, and salt. Mix on low speed, gradually increasing the speed to medium, until the dough just comes together, about 1 minute.
2. 2
   Divide the dough in half and form each half into a disk. Wrap each disk tightly in plastic wrap and refrigerate for at least 1 hour. You will only need 1 disk for this recipe. Refrigerate or freeze the second disk for another use.
3. 3
   Heat the oven to 350°F and arrange a rack in the middle. Lightly flour a clean work surface and roll out 1 disk of dough into a 12-inch round approximately 1/4 inch thick. Line a 9-1/2-inch deep-dish pie plate with the dough, trimming within 1 inch of the plate. Fold the excess dough under and pinch to create a decorative edge. Place in the refrigerator while the oven finishes heating up, at least 15 minutes.
4. 4
   Line the crust with a piece of parchment paper or aluminum foil large enough to overhang the edge by 1 inch, then fill it with pie weights or dried beans. Bake until the crust is set and light brown, about 20 minutes. Remove the pie weights and parchment paper or foil and continue baking until the crust is dry to the touch, about 8 to 10 minutes more. Place on a rack and cool completely.

For the spice mix:

1. 1
   Place the cinnamon stick, star anise, cloves, coriander, juniper berries, Sichuan peppercorns, and cardamom seeds in a small frying pan over medium heat and toast, shaking the pan occasionally, until fragrant, about 3 minutes. Let cool completely.
2. 2
   Transfer to a spice or coffee grinder and grind into a fine powder. Place in a small bowl, add the ground ginger and citrus peels, and stir to combine; set aside.

For the pumpkin filling:

1. 1
   Heat the oven to 350°F and arrange a rack in the middle.
2. 2
   Place the eggs in a large bowl and whisk until the yolks are broken up. Add the condensed milk, 2 cups of the pumpkin purée, and 2 3/4 teaspoons of the spice mix and whisk until smooth. (Store the remaining spice mix in an airtight container in the freezer.)
3. 3
   Pour the pumpkin mixture into the prepared pie crust. Bake until the filling is set in the middle and the edges are puffed, about 50 to 60 minutes. Remove to a wire rack and let cool to room temperature. Meanwhile, make the walnut–brown sugar topping.

For the walnut–brown sugar topping:

1. 1
   Heat the oven to 350°F and arrange a rack in the middle.
2. 2
   Place the brown sugar, flour, and salt in a medium bowl and stir to combine. Using a pastry blender or your fingers, cut the butter into the dry ingredients until reduced to pea-size pieces. Add the walnuts and toss with your fingers to combine.
3. 3
   Squeeze clumps of the mixture between your fingers to form irregularly shaped pieces about the size of a cashew. Turn the mixture out onto a baking sheet. Bake until golden brown and the nuts are toasted, about 8 minutes. Place the pan on a rack and scrape up the streusel from the pan with a flat spatula, then spread again into an even layer. Cool completely and sprinkle evenly over the pie.