1. Prepare the Crust and Oven:

For the crust: Preheat the oven to 325°F (160°C).

Wrap heavy-duty foil around the bottom and sides of a 9-inch springform pan. This will prevent water from seeping into the pan during the water bath.

Spray the inside of the pan lightly with nonstick cooking spray.

2. Make the Graham Cracker Crust: In a medium bowl, stir together the graham cracker crumbs, melted butter, granulated sugar, and kosher salt.

Press the mixture into the bottom and 1 inch up the sides of the prepared springform pan. Use the bottom of a measuring cup or your fingers.

Bake the crust until golden brown, 10 to 12 minutes.

Cool completely on a wire rack, about 30 minutes.

3. Prepare the Water Bath:

Bring a large pot of water to a simmer over medium-low heat. This will be used for the water bath.

4. Make the Key Lime Filling: In the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer and a large bowl), beat the softened cream cheese on medium speed until no lumps remain, about 2 minutes.

Add the sour cream, granulated sugar, all-purpose flour, and kosher salt.

Beat until the batter is smooth and creamy, about 1 minute. Scrape down the sides and bottom of the bowl with a rubber spatula.

5. Add Eggs and Flavorings:

Add the eggs one at a time. Beat on low speed until just combined after each addition. Continue scraping down the sides and bottom of the bowl as needed. Be careful not to overbeat.

Stir in the vanilla extract, key lime zest, and key lime juice.

6. Assemble and Bake in Water Bath:

Pour the filling into the cooled graham cracker crust.

Place the springform pan inside a large roasting pan.

Place both pans into the oven.

Quickly pour the hot simmering water into the roasting pan so that it comes about halfway up the foil-wrapped springform pan. This creates a water bath.

Bake for 1 hour 20 minutes to 1 hour 30 minutes. Or until the cheesecake is set on the sides and just barely jiggles in the center when the pan is shaken.

7. Cool Slowly:

Turn the oven off and crack the oven door open.

Leave the cheesecake in the oven for 15 minutes. This helps to prevent cracking.

8. Cool Completely:

Remove the cheesecake from the water bath.

Carefully remove the foil from the springform pan.

Transfer the cheesecake to a wire rack.

Let the cheesecake continue cooling to room temperature, about 2 hours.

9. Chill: Place the cheesecake in the refrigerator for at least 8 hours, or preferably overnight, to chill completely.

10. Make the Whipped Cream Topping: Just before serving, make the whipped cream topping.

In the bowl of a stand mixer fitted with a whisk attachment (or using a hand mixer and a large bowl), beat the cold heavy whipping cream until thickened.

Add the granulated sugar and vanilla extract.

Beat the cream on high speed until medium peaks form.

11. Decorate and Serve: Run a thin knife or offset spatula along the edge of the pan, between the cheesecake and the pan, before removing the sides of the springform pan.

Top the chilled cheesecake with the whipped cream. Garnish with key lime zest and key lime slices, if desired.

Slice and serve. Enjoy your incredibly delicious Key Lime Cheesecake!