On a lightly floured surface, roll dough into a 14-inch circle. Fold into quarters; unfold in prepared pie pan. Poke all over with the tines of a fork. Line shell with tin foil and add pie weights, beans, or rice as pie weights. Bake 12 minutes, remove weights and foil, and bake 10 minutes more or until crust is set and hasn’t browned in the least. Remove from oven and set aside while you make filling.

Set oven to 375 degrees F.

In a large bowl, combine pumpkin or squash puree, butter, lemon juice, ground ginger, nutmeg, cinnamon, and sea salt. Beat with a whisk until well-combined and fluffy.

In a small bowl, combine egg yolks and sugar, whisk together a minute or so and set aside.

Pour egg yolk mixture into the puree mixture; beat with a whisk until smooth and light. Slowly fold in flour, followed by the buttermilk.

Meanwhile, with clean, dry beaters, whisk reserved egg whites to soft peaks, and fold into filling.

Spoon filling into the baked shell, and bake 35 - 40 minutes or just until the very center is set – it should have some movement, but not still seem like a liquid.

Cool 2 - 3 hours, slice, and serve.