Pumpkin Ice Cream Gingersnap Pie

• Pumpkin Ice Cream Gingersnap Pie
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• COOKIE CRUST
• Butter and flour for pan
• 7 ounces gingersnaps
• 1 tablespoon sugar
• 4 tablespoons salted butter, melted
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• PIE FILLING & TOPPING

• 4 cups packed vanilla-bean ice cream (bear in mind that airy ice cream will collapse more, so buy a little extra)
• 1 cup canned pumpkin-pie mix*
• 1/2 cup whipping cream
• 1 tablespoon sugar
• 1/4 cup finely chopped crystallized ginger

1. Preheat oven to 325.° Make crust: Butter and lightly flour a 9-in. sturdy metal pie pan. In a food processor, whirl cookies with sugar into fine crumbs. Drizzle in butter and whirl, scraping bottom of bowl occasionally, until crumbs come together.2. Press crumb mixture evenly and firmly over bottom, up sides, and slightly higher than rim of pie pan (don't press over rim, or it will crumble when cut). Press rim firmly together. Run a spoon around bottom inner edge of pie, scooping away extra crumbs; otherwise the crust tends to get too thick.

3. Bake crust until firm and lightly toasted, 12 to 14 minutes. Let cool.

4. Make filling: In a large bowl, mash ice cream to an even consistency with a metal pastry blender or large fork. Stir in pie mix, then freeze until the consistency of soft-serve ice cream. This takes anywhere from 15 minutes to 1 ½ hours depending on ice-cream type and whether you’re using pumpkin-pie filling (takes longer due to the added sugars) or canned pureéd pumpkin.

5. Carefully dollop ice cream into center of cooled crust and spread outward, not quite but almost to edge (the ice cream will naturally settle outward to fill the crust). With a small metal spatula, swirl the top into waves if you like. Slide into freezer, making sure pie is level; otherwise it will freeze lopsided. Freeze at least 4 hours and up to 1 week (cover if more than 4 hours).

6. Up to 2 hours before serving, whip cream with sugar into soft peaks. Chill until ready to use.

7. A few minutes before serving, take pie out of freezer to soften. Cut into slices and top each with whipped cream and a big pinch of crystallized ginger.

Make ahead: Pie, up to 1 week, covered with plastic wrap and frozen. Whipped cream, up to 2 hours.

*Or use 1 cup canned puréed pumpkin mixed with 1/2 tsp. each ground cinnamon, allspice, and ginger, plus 1/4 tsp. each cloves and nutmeg.