Preheat your oven to 300°F. Position your oven racks above and below the middle position, preparing your space for baking.
Lightly spray a 9-inch springform pan with cooking spray to ensure easy removal later.
In a bowl, mix together the graham cracker crumbs, sugar, and melted butter until well combined. Press this mixture firmly into the bottom and up the sides of your springform pan. Bake in the preheated oven for 15 minutes and then let it cool.
Next, in a larger bowl, beat the softened cream cheese, granulated sugar, cornstarch, and lime zest until smooth and creamy. Then, add the key lime juice and mix in the eggs one at a time until just combined.
Pour this delicious filling into the cooled crust and spread it evenly.
To create a nice moist environment for the cheesecake, place a pan filled with 3 cups of boiling water on the bottom oven rack. Then, place your cheesecake on the upper rack and bake for 55-65 minutes.
Once the time is up, turn off the oven, prop open the door slightly, and allow the cheesecake to cool in the oven for 30 minutes. Remove it, let it cool completely on a wire rack, then refrigerate overnight.
For the final touch, beat the heavy whipping cream with powdered sugar until you form stiff peaks. Garnish the cooled cheesecake as desired with this fluffy whipped cream and, if you like, some extra lime zest or slices.