Make pumpkin pie puree
Preheat oven to 400F. Cut the pumpkin in half. Scoop out the seeds and stringy bits. Place the halves face down on a baking sheet. Bake until soft, about 30-90 minutes, depending on how thick the pumpkin is. Scoop the flesh from the pumpkin and mash with fork. Let cool. Put aside 2 cups for the pie and reserve the rest for another use.
Reduce oven temperature to 375F. Line shell with foil and fill with pie weights. Bake in middle of oven 20 minutes. Remove weights and foil and bake shell until pale golden, 6 to 10 minutes more. Cool in pan on a rack. Whisk together pumpkin, cream, milk, eggs, brown sugar, spices, and salt, then pour into shell. Bake pie in middle of oven 45 to 50 minutes, or until filling is set but center still trembles slightly. (Filling will continue to set as pie cools.) Transfer to rack and cool completely.