01 - Preheat oven to 350°F.
02 - Combine graham cracker crumbs, sugar, and melted butter in a medium bowl. Mix until evenly moistened.
03 - Press mixture firmly into bottom and up sides of a 9-inch pie dish. Bake for 8-10 minutes until lightly golden. Cool slightly.
04 - Whisk together sweetened condensed milk, egg yolks, key lime juice, lime zest, and green food coloring until smooth and fully combined.
05 - Pour filling into cooled crust and smooth the top.
06 - Bake for 12-15 minutes until center is set but still slightly wobbly.
07 - Remove from oven, cool to room temperature, then refrigerate for at least 3 hours.
08 - Beat cold heavy cream, powdered sugar, and vanilla extract until soft peaks form.
09 - Spread or pipe whipped cream over chilled pie.
10 - Garnish with lime zest and lime slices. Serve chilled.