Step 1

For the pie dough: Pulse the flour, shortening, sugar, vinegar and salt in a food processor until it looks like fine meal. Add the butter and pulse until pea-size pieces remain. Sprinkle in 2 tablespoons ice water and pulse until the dough begins to come together. Pinch the dough with your fingers; if it doesn't hold together, add up to 2 more tablespoons ice water, 1 tablespoon at a time, pulsing after each addition.

Step 2

Put the dough on a large piece of plastic wrap and pat into a disk. Wrap tightly and refrigerate until firm, at least 1 hour or preferably overnight. (The dough can also be frozen for up to 2 months.)

Step 3

Lightly flour a work surface. Roll out the chilled dough into a 12-inch round and transfer to a 9-inch pie plate. Fold the overhanging dough under itself and crimp the edges with your fingers. Pierce the bottom and sides all over with a fork. Chill at least 1 hour and up to overnight. (If refrigerating overnight, cover with plastic wrap.)

Step 4

Preheat the oven to 350 degrees F. Line the chilled dough with foil and fill with pie weights or dried beans. Bake until the edges are golden, 20 to 25 minutes. Remove the foil and weights and continue baking until the crust is golden all over, 10 to 15 minutes more. Transfer to a wire rack to cool completely.

Step 5

For the filling: Gently whisk the pumpkin, cream, granulated sugar, eggs, cinnamon, nutmeg, vanilla and salt in a large bowl until just smooth (do not overmix). Pour the filling into the cooled crust and smooth the top. Bake until the filling is set around the edges but still slightly jiggly at the center, 50 minutes to 1 hour. Transfer to a rack to cool completely.

Step 6

For the marshmallow meringue: Bring a few inches of water to a simmer in a medium saucepan. Add the egg whites to the bowl of a stand mixer fitted with the whisk attachment along with the sugar, cream of tartar and salt. Whisk to combine. Remove the bowl from the stand mixer base and place over the simmering water (make sure the bottom of the bowl is not touching the water). Cook, whisking constantly, until the sugar is completely dissolved and the mixture feels hot to the touch. Return the bowl to the stand mixer and whisk on medium-high speed until stiff peaks form, 5 to 6 minutes. Add the marshmallow fluff and vanilla, then beat on medium-high until just combined.

Step 7

Gently mound the meringue on top of the filling. Use an offset spatula to spread the meringue all the way to the edges of the crust to completely cover the filling, then make decorative swirls and peaks. Toast the meringue using a kitchen torch or broil 1 to 2 minutes until golden brown (watch the meringue closely if broiling to prevent burning). Slice the pie into wedges and serve.