Prepare the Crust:

• Preheat your oven to 350°F (175°C).
• Mix graham cracker crumbs, sugar, and melted butter in a bowl until well combined.
• Press the mixture into a 9-inch pie dish, forming a firm, even layer on the bottom and up the sides.
• Bake the crust for 10 minutes, then remove from the oven and allow to cool slightly.

Make the Filling:

• In a mixing bowl, beat the egg yolks until they are light and fluffy.
• Add the sweetened condensed milk, key lime juice, and key lime zest, and continue to beat until thoroughly combined.
• Pour the filling into the cooled crust.

Bake the Pie:

• Bake the pie for 15 minutes, or until the filling is set but still slightly jiggly in the center.
• Remove from the oven and allow to cool to room temperature. Once cooled, refrigerate the pie for at least 3 hours, until fully chilled and set.

Prepare the Whipped Cream Topping:

• In a mixing bowl, whip the heavy cream and powdered sugar until stiff peaks form.
• Spread or pipe the whipped cream over the chilled pie before serving.

Serve:

• Garnish with additional lime zest or lime slices if desired.
• Slice and serve chilled.