To use fresh pumpkin, halve and place a 1 3/4-pound sugar pumpkin, cut sides down, in a baking pan. Roast in a 400 degree oven until very soft, 50 to 60 minutes. Scoop out flesh and puree in a food processor until very smooth.
On a lightly floured work surface, roll out one disk of dough to a 12-inch round. With a dry pastry brush, sweep off excess flour; fit dough into a 9-inch glass pie plate, pressing into the edges. Trim dough to meet the edge of the pie plate. Prick the bottom of the dough all over with a fork. On a lightly floured piece of parchment, roll out the other disk of dough. Transfer dough (on parchment) to a baking sheet. Chill pie shell and dough until firm, about 30 minutes.
Using a triangle-shaped cutter or a sharp knife, cut out about 40 triangles (each side about 1-inch long) from the sheet of dough. In a small bowl, whisk together the egg yolk and 1 tablespoon water; lightly brush the bottoms of the triangles with egg wash, and gently press, slightly overlapping, to adhere to the dough, until the entire rim is covered. Lightly brush the decorated edge with egg wash; don't let it pool. Chill pie shell until firm, about 30 minutes. Meanwhile, preheat the oven to 375 degrees.
Line shell with parchment paper, leaving a 1-inch overhang. Fill with pie weights or dried beans. Bake until the edges are just beginning to turn golden, 15 to 20 minutes. Remove parchment and weights. Return crust to the oven; continue baking until light golden all over, 15 to 20 minutes more. Cool completely on a wire rack.
Reduce oven temperature to 350 degrees. In a large bowl, whisk together pumpkin, sugar, cinnamon, ginger, salt, nutmeg, whole eggs, and evaporated milk until combined. Pour mixture into the cooled crust, and bake until the filling is set around the edges but still slightly soft in the center, 40 to 45 minutes. (Check crust periodically; if it gets too dark, cover the edges with foil.) The filling will be just slightly loose in the center, but will firm up as it cools. Transfer to a wire rack to cool completely.