Step 1

Preheat oven to 350ºF.

Step 2

Combine graham cracker crumbs and sugar in medium bowl. Stir in melted butter until well-combined. Press into the bottom and up the sides of a 9 in. pie pan.

Step 3

Bake crust 8-10 minutes or until lightly browned. If crust bubbles up, gently press back into place with a spoon. Cool in pan on cooling grid 15-20 minutes. Reduce oven temperature to 325°F.

Step 4

Whisk together sweetened condensed milk, key lime juice, sour cream, egg yolks and lime zest in a medium bowl. Pour into cooled crust. Bake 20-23 minutes or until filling is mostly set. Cool in pan on cooling grid, then chill completely.

Step 5

Shortly before serving, prepare topping. In a large bowl, whip cream with powdered sugar until stiff peaks form. Fill a decorating bag fitted with tip 1M with whipped cream and pipe border onto pie. Garnish with additional lime zest and slices, if using.