Preheat the oven to 350°F (175°C). In a bowl combine the Graham Cracker Crumbs with Granulated Sugar, a pinch of Salt and melted Unsalted Butter; press the mixture firmly into a 9-inch pie pan to form an even crust and bake for 8–10 minutes until set, then let cool slightly.
In a separate bowl whisk the Egg Yolks until smooth, then gradually whisk in the Sweetened Condensed Milk until fully combined and creamy.
Stir in the Key Lime Juice, the Key Lime Zest and another small pinch of salt, mixing until the filling is homogeneous; pour the filling into the warm crust and smooth the top.
Bake the pie for 12–15 minutes, or until the edges are set and the center still has a slight jiggle. Remove from the oven, cool to room temperature, then refrigerate for at least 2 hours (longer is fine) to chill and finish setting.
Just before serving whip the Heavy Cream with the Powdered Sugar and Vanilla Extract to soft peaks, then spread or pipe over the chilled pie.
Garnish with additional key lime zest and thin slices or wedges of Lime; slice and serve cold. Store any leftovers covered in the refrigerator for up to 3 days.
