PreparationFor crust: Position rack in center of oven and preheat to 350°F. Mix gingersnap cookie crumbs, sugar, and ginger in medium bowl. Add melted butter and stir until mixture is evenly moistened. Transfer crumb mixture to 9-inch-diameter glass pie dish; press crumbs firmly and evenly onto bottom and up sides to top of dish. Bake until crust is firm and slightly darker in color, about 8 minutes. Cool crust completely. For filling: Pour enough cold water into medium bowl to come halfway up sides; add 2 cups ice cubes and set aside. Pour 1/4 cup water into small bowl; sprinkle gelatin over. Let stand until gelatin softens, about 15 minutes. Whisk 3/4 cup sugar, lemon juice, egg yolks, grated lemon peel, and salt in heavy medium saucepan to blend. Whisk constantly over medium heat until mixture thickens very slightly (mixture will coat spoon but will not be thick like curd) and thermometer inserted into mixture registers 160°F, about 6 minutes (do not boil). Add gelatin mixture; whisk until gelatin dissolves and mixture is smooth, about 1 minute. Place saucepan in bowl with ice water until lemon filling is cool to touch, whisking occasionally, about 8 minutes. Transfer lemon filling to large bowl. Using electric mixer, beat whipping cream with powdered sugar in another medium bowl until peaks form. Fold 1/4 of whipped cream into lemon filling until incorporated. Fold in remaining whipped cream in 3 additions. Transfer filling to cool crust, mounding slightly in center. Refrigerate pie until filling is set, about 4 hours. Do ahead: Can be made 1 day ahead. Keep refrigerated. Let stand at room temperature 20 minutes before serving. Toss lemon peel strips with remaining 2 tablespoons sugar in small bowl; let stand 10 minutes. Twist peel to form curls (see tip below). Garnish center of pie with lemon peel curls. To make lemon peel curls: Remove peel in long strips using a citrus zester or channel knife. Twist strips around chopstick to form curls, then slide curls off.