How to Make It
In a large bowl, whisk the flour with the salt. Rub in the butter until the mixture resembles coarse meal. In a cup, beat the egg yolk with 3 tablespoons of the water; drizzle over the flour mixture and stir with a fork. Press the crumbs together to form a rough dough, adding the remaining 1 tablespoon of water if needed. Scrape the dough onto a lightly floured work surface, gather up any crumbs and knead gently just until the dough comes together. Pat the dough into a disk, wrap in plastic and refrigerate until firm, about 1 hour.
Preheat the oven to 400°. On a lightly floured work surface, roll out the dough to a 12-inch round. Fit the dough into a deep 9-inch glass pie plate. Trim the overhanging dough to 1 inch. Fold the dough under itself and crimp decoratively. Prick the dough all over with a fork and chill for 10 minutes.
Line the pie shell with parchment paper and fill with pie weights or dried beans. Bake for about 15 minutes, or until set. Remove the pie weights and bake for about 10 minutes longer, or until the shell is golden. Reduce the oven temperature to 325°.
In a large bowl, whisk the pumpkin puree with 2/3 cup of the sugar and the half-and-half, whole eggs, egg yolks, molasses, pie spice and salt. Pour the filling into the hot pie shell and bake for 1 to 1 1/4 hours, or until the center is just set and the edges are slightly puffed. Transfer the pie to a rack and let cool to room temperature.
In a medium bowl, whisk the heavy cream with the crème fraîche and the remaining 1 tablespoon of sugar until it holds soft peaks. Serve the pie with the whipped cream.