Preheat oven to 325 degrees. Whisk together pumpkin, heavy cream, sugar, vanilla, salt, cinnamon, ginger, allspice, and eggs in a large bowl. Pour filling into prepared pie crust.
Place dish on a rimmed baking sheet. Bake, rotating halfway through, until filling is just set and slightly puffed but still a bit wobbly, 55 to 60 minutes. Transfer to a wire rack, and let cool completely. Refrigerate, uncovered, for at least 6 hours. Serve chilled, topped with whipped cream if desired.