How to Make It
Preheat oven to 350°. Combine cracker crumbs, sugar, and 1/8 teaspoon salt in a bowl, stirring well to combine. Drizzle butter over crumb mixture; toss with a fork until crumbs are moist. Press crumb mixture into bottom and up sides of a 9-inch glass or ceramic pie dish. Bake 8 minutes; let cool on a wire rack.
Whisk together 1/3 cup cream, 2 teaspoons lime zest, lime juice, milk, eggs, and remaining 1/8 teaspoon salt in a bowl until smooth. Pour mixture into cooled crust. Bake 15 minutes. Remove from oven; let cool 15 minutes. Refrigerate 2 hours or until set.
Combine powdered sugar, vanilla, and remaining 2/3 cup cream in a bowl. Beat with an electric mixer at high speed until soft peaks form. Dollop pie with whipped cream; garnish, if desired.