In a food processor, pulse cookies until a fine crumb forms. Add melted butter, brown sugar and nutmeg. Pulse until combined. Dump into a 9" pie plate and spread and flatten with a fork or your hands to form crust on the bottom and up the sides of the pan.
In a large bowl, whip heavy cream until stiff peaks form. Beat in powdered sugar and nutmeg. Set aside.
In a separate large bowl, whisk vanilla pudding mix and eggnog together. Whisk in whipped cream until mixture is smooth. Pour on top of gingersnap crust.
Cover the pie with plastic wrap and freeze for 4-5 hours. When ready to serve, remove from the freezer and allow to soften for at least 10 minutes before serving. Don't wait too long or the pie will get too soft to cut into clean slices. (But... will still be just as delicious.)