Preheat oven to 375°.
Place pumpkin halves cut side down on a baking sheet lined with parchment paper. Bake until skin is softened and can be pierced easily with a fork (about 40 minutes). Remove from oven and cool. Scoop out pumpkin flesh and discard skin.
Place 2 cups of mushy pumpkin into a food processor fitted with a steel blade (save any remainder for pancakes, pie, etc.). Add both sugars and purée until very smooth. (If needed, add a bit of liquid from the roasted pumpkin to achieve a finely textured purée.)
In a separate bowl, beat the eggs thoroughly until eggs run off the whisk like water. Add milk and whisk until blended. Add pumpkin purée, spices and salt and whisk until well incorporated. Pour into a blind-baked pie shell and refrigerate until baking.
To bake pie, preheat oven to 400°. (If using a convection oven, turn the fan off or set to low.) Bake for 7 minutes and reduce heat to 325°. Bake for 35 minutes, then check for doneness, returning to oven if needed. When the filling is firm around the edge and the middle jiggles like Jell-O, it’s done. Cool completely on a wire rack, about 2 hours minimum before serving.
Recipe by Owner/Baker Daniel Sheehan, Humble Pie Company, Providence