We prefer the sweet flavorful flesh of the kabocha squash over any other pie pumpkin. The chestnut-like texture of this pie makes it especially toothsome.
For the crust
For the filling
For the pie crust, whisk the flour, salt, and sugar in a mixing bowl. Work the butter and shortening into the flour using a pastry blender, 2 butter knives, or your fingertips until it resembles coarse cornmeal. Sprinkle in 5 tablespoons ice water and toss together lightly until the dough comes together (add a little more ice water if needed). Shape the dough into a flat disk; don’t overhandle. Wrap the dough in plastic wrap, and chill for at least 1 hour.
Preheat the oven to 400°. Cut the squash in half horizontally. Scoop out and discard the seeds. Place the squash cut side down on a baking pan and add a splash of water to the pan. Bake the squash until tender when poked with a knife, about 1 hour. Remove from the oven, set aside, and allow to cool. Reduce the oven heat to 375°.
When the squash is cool enough to handle, scoop out enough flesh to measure 2 1/2 cups. Put the flesh into a large bowl. Discard the skins. Add the brown sugar, molasses, egg yolks, cream, ginger, cinnamon, mace, and salt, and mix together well.
Roll out the dough into a 12-inch round on a lightly floured surface. Roll the dough loosely around the rolling pin then unfurl it into a 9-inch pie pan. Lightly press it into the pan. Leave 1 inch of dough hanging over the edge. Trim any excess off with a sharp knife. Tuck the dough under itself, then use your thumb and forefinger to crimp the edge.
Pour the filling into the unbaked pie shell and smooth the top with a rubber spatula. Bake for 1 hour. Mix the sugar and cinnamon together in a cup. Sprinkle the top of the pie with cinnamon sugar. Serve with whipped cream.