Crust

1. Preheat the oven to 350F and grease the inside of a 9” springform pan. Remove the ring, place a sheet of parchment paper down on the bottom plate, and return the ring to secure the paper in place.
2. In a large bowl, stir together the ground graham crackers, sugar, and salt. Then stir in the melted butter until evenly hydrated.
3. Remove 2 tablespoons of the mixture and store in the refrigerator (we’ll use this for decoration later). Now dump 2/3 of the mixture into the springform pan and pack it into the bottom and all the way up the sides. Bake for 8 minutes.
4. To the remaining crust, mix in the lime zest and set to the side.
5. Once the crust is baked, reduce the oven to 325F. 

Key Lime Cheesecake Filling

1. In a large bowl using a hand or stand mixer with the paddle attachment, mix the cream cheese, sugar, and cornstarch on low speed until just combined.
2. Scrape down the bowl and add in the vanilla, lime zest, and sour cream. Mix again on low speed just until combined. 
3. Now to the oven, place a large roast pan on the bottom rack and place a medium pot full of water over high heat. By the time the batter is prepared, the water will be boiling and ready for our water bath.
4. Back to the batter. Scrape down the bowl and as the mixer is running on low speed, slowly pour in the lime juice until incorporated.
5. Crack the eggs into a pourable glass and lightly beat with a fork. With the mixer running on low speed, slowly pour in the eggs and mix until just combined.
6. Use your rubber spatula to scrape down the bowl and give the batter one last good mix by hand. 
7. Pour half of the batter into the baked crust. Top with a layer of the remaining graham cracker crust and gently spread it even. 
8. Cascade the rest of the cheesecake batter on top, careful not to pour it all into one spot so it doesn’t sink through the crust. Spread even. 
9. Carefully pour the boiling water into the roast pan at the bottom of the oven and quickly place the cheesecake on the middle rack just above the pan. 
10. Bake for 1 hour to 1 hour and 15 minutes, until the edges are golden and the center jiggles when judged. Then turn off the oven and crack open the door, leaving the cheesecake inside for 1 hour.
11. After the hour, transfer the cheesecake to the refrigerator to chill uncovered overnight.

Whipped Topping

1. Before serving, top with the whipped cream (or serve it on the side).
2. In a large bowl using a hand or stand mixer with the whisk attachment, whip the heavy cream and powdered sugar on high speed until fluffy but smooth.
3. Spread or scoop the whipped cream on top of the cheesecake and sprinkle with lime zest and reserved graham cracker mixture. Slice and enjoy!