Pumpkin Chiffon Pie

Heat the oven to 350°F and arrange a rack in the middle.

Place the cookies in a food processor fitted with a blade attachment and process into fine crumbs (you should have about 2 cups). Stop the motor, add the melted butter, and pulse to combine. (Alternatively, place the cookies in a resealable plastic bag, press out the air, and seal. Using a rolling pin, smash into uniform fine crumbs.

Transfer to a medium bowl, add the melted butter, and mix until evenly combined.)

Pour the crumb mixture into a 9-1/2-inch deep-dish pie plate and, using the bottom of a cup or your fingers, press firmly and evenly into the bottom and up the sides.

Bake until fragrant and slightly darkened in color, about 10 to 15 minutes.

Pour the rum or apple cider into a small bowl and sprinkle the gelatin evenly over the surface; set aside.

Whisk the pumpkin, milk, brown sugar, egg yolks, spices, and salt together in a medium saucepan over medium heat. Cook, whisking constantly, until the mixture just starts to steam and reaches 160°F on an instant-read thermometer, about 8 to 9 minutes (do not let the mixture simmer).

Remove the pan from the heat, add the rum-gelatin mixture, and whisk until combined and the gelatin has dissolved, about 1 to 2 minutes.

Transfer the mixture to a large bowl and let cool for 15 minutes.

Place the egg whites in the bowl of a stand mixer fitted with a whisk attachment.

Whisk on high speed until medium peaks form, about 1 minute. With the mixer still on high speed, slowly add the sugar and continue whisking until stiff, glossy peaks form, about 1 1/2 minutes more.Using a rubber spatula, add half of the beaten egg whites to the cooled pumpkin mixture and gently stir until just combined.

Add the remaining egg whites and gently stir until just combined and no streaks of egg white remain.

Transfer the chiffon mixture to the prepared pie crust and spread it into an even layer. Refrigerate uncovered until set, at least 6 hours or overnight.To assemble:When ready to serve, place the cream, sugar, and rum or apple cider in the bowl of a stand mixer fitted with a whisk attachment.

Whisk on medium speed until medium peaks form, about 3 minutes.

Spread evenly over the pie and serve immediately.