In a mixing bowl, add the graham cracker crumbs, sugar, and melted butter. Stir until the butter coats all the crumbs.
Press the crumbs into a 9.5-inch springform pan. Press the crumbs up the side of the pan as well as the bottom of the pan.
Place in the oven and let bake for 15 minutes.
Remove from the oven and let cool.
In a mixing bowl, add in the cream cheese and granulated sugar. Mix until completely incorporated. Scrape the sides and bottom of the bowl and mix again to avoid any lumps of cream cheese in your batter.
Add in the eggs one at a time. Mix each egg completely before adding the next. Scrape down the bowl after adding each egg.
Add in the key lime juice and sweetened condensed milk. Mix until incorporated.
Line the outside of the springform pan with heavy duty tin foil. I double wrap it to prevent the water from leaking in.
Pour the cheesecake filling into the cooled crust.
Place the springform pan in a slightly larger baking pan. Fill the outer pan with about an inch of water.
Place in the oven at 325 degrees and let bake for 1 hour and 15 minutes or until done. To make sure the cheesecake is done, gently give it a wiggle. If it slightly jiggles in JUST the middle like jello, then it's done. If it jiggles all over, it needs to bake longer. Turn off the heat and crack the oven door slightly. Let it cool in the oven for an hour or two. I kept mine in the oven for about 2 and half hours and then placed it in the fridge.
In a mixing bowl, add in the heavy cream. Beat until soft peaks form.
Add in the powdered sugar. Continue to beat until it becomes thick.
Add the whipped cream into a piping bag with a 1M tip. Pipe the whipped cream on top of the cheesecake.
Sprinkle the zest on top of the cheesecake.
Add the quartered pieces of lime in between the swirls of whipped cream.
If the limes are damp, dry them off before adding them to the whipped cream.