Favorite Thanksgiving Recipes - Pumpkin Chiffon

This one's for you, Emily. I'm not crazy about pumpkin pie, but this is definitely worth the calories.

Pumpkin Chiffon Pie with Gingersnap Crust
adapted from Ruth Reichl, The Gourmet Cookbook, pg. 768

FOR CRUST:

20 (2-inch) gingersnaps, finely ground
1/2 stick (4 tablespoons) unsalted butter, melted and cooled

FOR FILLING:

3 1/2 teaspoons unflavored gelatin (from two 1/4-ounce envelopes)
1/4 cup apple cider
6 large eggs, separated
3/4 cup packed light brown sugar
2 1/4 cups solid-pack pumpkin (from one 29-ounce can or two 15-ounce cans)
1 1/2 teaspoons ground cinnamon
3/4 teaspoon ground ginger
3/4 teaspoon freshly grated nutmeg
1/2 teaspoon salt
1/2 cup granulated sugar
1 1/2 cups very cold heavy cream

SPECIAL EQUIPMENT
9 to 9 1/2 inch springform pan; instant read thermometer

MAKE THE CRUST: Put a rack in the middle of oven and preheat oven to 350 degrees F. Invert bottom of springform pan (to make it easier to slide pie off bottom), then lock on side and batter pan.

Stir together gingersnap crumbs and butter in a bowl until crumbs are evenly moistened. Press on to bottom of springform pan. Bake until edges are golden brown, about 8 minutes (watch carefully toward end of baking; crust burns easily). Cool in pan on a rack.

MAKE THE FILLING: Sprinkle gelatin over cider in a small bowl and let soften for 1 minute.

Beat together yolks and brown sugar in a large bowl with an electric mixer at high speed until thick and pale, 3 to 5 minutes. Reduce speed to medium and mix in pumpkin, spices, and salt.

Transfer pumpkin mixture, and stir until it is dissolved. Transfer to a large metal bowl set in a larger bowl of ice and cold water and cool, stirring occasionally, until mixture is the consistency of raw egg whites, about 15 minutes. Remove from ice bath.

Beat egg whites in another large bowl with cleaned beaters at high speed until froth. Gradually add granulated sugar and beat until whites hold stiff, glossy peaks. Gently bu thoroughly fold into pumpkin mixture.

Beat cream in another large bowl with cleaned beaters until it just holds stiff peaks. Gently but thoroughly fold into pumpkin mixture. Pour filling into springform pan and smooth top. Refrigerate, uncovered, for 1 hour, then cover and refrigerate until pie is set, at least 3 hours.

Before serving, run a thin knife around edge of pie and remove side of pan. Garnish with whipped cream and crystallized ginger, if desired.