Position oven rack 1/3 up from the bottom of the oven; preheat to 450°. Have the crust in the freezer for at least 20-30 minutes before baking (or longer).
Add cream to a small saucepan, uncovered, over medium heat; let stand until a slightly wrinkled skin forms on top or tiny bubbles appear around the edges.
Meanwhile, in a bowl of an electric mixer, beat the eggs lightly just to mix; beat in the vanilla, sugar, and salt.
Through a fine strainer, add the spices; then add the pumpkin and mix well.
Gradually stir in the hot cream.
Do not remove the pie crust from the freezer until you are ready to bake it.
Pour the pumpkin mixture into the frozen crust.
Bake for 10 minutes at 450°, then decrease oven temperature to 350° and bake 30-40 minutes longer until a small sharp knife gently inserted into the middle of the pie comes out clean (every time you test the pie with a knife it will leave a scar that will increase in size as the pie cools; do not cut more than necessary).
Place the baked pie on a rack; serve while still barely warm or at room temperature.
In a chilled bowl with chilled beaters, whip together the cream, sugar, and vanilla.
If the pie is still slightly warm when you serve it, it is best to serve the whipped cream separately (the heat of the pie would melt the cream).
Whip the cream until it is no too stiff, it should barely hold a shape and should be more like a thick sauce.
But if the pie has cooled to room temperature, the cream can be whipped until it holds a definite shape and can be spread over the top of the pie.
Either way, the cream can be whipped a few hours ahead, refrigerated, and then whisked a bit with a small wire whisk just before serving.