01 - Preheat oven to 350°F. Combine graham cracker crumbs, sugar, and melted butter in a bowl. Press mixture firmly into a 9-inch pie dish, covering the bottom and sides evenly.
02 - Bake the crust for 8 minutes until lightly golden. Remove from oven and let cool slightly while preparing the filling.
03 - Whisk together egg yolks and lime zest for 2 minutes until pale in color. Slowly whisk in sweetened condensed milk until incorporated. Add lime juice and salt, mixing until smooth and slightly thickened.
04 - Pour filling into the cooled crust. Bake for 12 minutes until the center is set but still slightly wobbly when gently shaken.
05 - Remove from oven and cool to room temperature, approximately 1 hour. Refrigerate for at least 3 hours or until completely chilled and set.
06 - Beat heavy cream, powdered sugar, and vanilla extract with electric mixer on medium-high speed until soft peaks form, about 3-4 minutes.
07 - Spread or pipe whipped cream over chilled pie. Garnish with additional lime zest if desired. Slice and serve cold.