Instructions: TO MAKE THE CRUST: Preheat the oven to 350 F. Lightly grease the bottom of a 10 x 3-inch springform pan with butter. Do not grease the sides of the pan. Wrap the outside of the pan with foil to prevent leakage. In a food processor, fitted with the steel blade attachment, pulverize the Graham crackers into crumbs. Transfer the crumbs to a mixing bowl, add the melted butter and mix with a rubber spatula. Press the crumb mixture over the bottom of the springform pan, reaching all the way to the sides so it forms a seal against leakage. Bake for 10 minutes, remove and cool while you make the filling; lower the heat to 325 F.

TO MAKE FILLING AND SWIRL TOP: With an electric mixer on low speed, beat the cream cheese and sugar for 2 minutes or until soft and creamy. Add the eggs, one at a time, beating for 15 seconds between additions to make sure each one is thoroughly incorporated. Scrape down the sides of the bowl with a rubber spatula and beat for a minute longer. With the machine running, slowly beat in the half and half and then 2 tablespoons of the Key Lime juice. Set aside 1/2 cup of the cheesecake mixture to which you should add the remaining Key Lime juice and transfer this to a liquid measuring cup or pitcher.

TO BAKE THE CAKE: Pour the cheesecake mixture over the baked crust, then pour a thin stream of Key lime-boosted cheesecake mixture over the top and scatter the grated lime zest over that. With a toothpick or wooden skewer, swirl the key lime mixture and zest into the batter the way you would marbleize a cake. Bake for 1 1/2 hours or until the mixture is set; the cake will appear jiggly, but will firm up upon standing.

TO COOL AND SERVE THE CAKE: Remove the cake from the oven and place on a rack to cool to room temperature in the pan. Unlock the springform and remove the cake, but leave the cake on the bottom of the pan. Chill in the refrigerator for at least 4 hours before serving or before attempting to remove the cake from the springform bottom.

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