Preheat oven to 350°F (175°C).
In a bowl, mix graham cracker crumbs, sugar, salt, and melted butter until evenly combined.
Press mixture firmly into the bottom and up the sides of a 9-inch pie pan.
Bake crust for 8 minutes, then set aside to cool.
In a large bowl, whisk egg yolks until slightly thickened.
Add condensed milk, lime juice, zest, vanilla, and salt.
Whisk until smooth and well blended.
Pour filling into cooled crust and smooth the top.
Bake for 12–15 minutes, until the center is just set but still has a slight jiggle.
Let cool at room temperature for 30 minutes, then refrigerate for at least 3 hours or overnight.
In a separate bowl, beat heavy cream, powdered sugar, and vanilla until stiff peaks form.
Once the pie is chilled, top with whipped cream and sprinkle with lime zest.
Slice and serve cold.