Preheat the oven to 350°F (175°C).

In a mixing bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until well combined.

Press the mixture firmly into the bottom of a 9-inch springform pan.

Bake for 10 minutes, then remove from oven and let cool.

In a large mixing bowl, beat the softened cream cheese until smooth.

Add sour cream, sugar, eggs, key lime juice, key lime zest, and vanilla extract. Beat until well combined and smooth.

Pour the filling over the cooled crust in the springform pan.

Place the springform pan in a baking dish filled with water (water bath) to prevent cracking.

Bake for 60 minutes, or until the center is set but slightly jiggly.

Turn off the oven and let the cheesecake cool in the oven with the door ajar for 1 hour.

Remove from the oven and refrigerate for at least 4 hours or overnight.

Top with whipped cream and garnish with additional key lime zest before serving.