Prep the pan and oven. Heat the oven to 325°F (163°C). Line the bottom of a 9-inch springform pan with parchment and lightly grease the sides.

Make the crust. Pulse graham crackers into fine crumbs. Stir in brown sugar and a pinch of salt, then mix in melted butter until the mixture feels like damp sand.

Press and pre-bake. Press crumbs firmly into the bottom and slightly up the sides of the pan. Bake for 8–10 minutes, just until set and fragrant. Cool while you make the filling.

Beat the cream cheese. In a large bowl, beat softened cream cheese on medium speed until completely smooth, 1–2 minutes. Scrape the bowl well to avoid lumps.

Add sugar and sour cream. Beat in granulated sugar until glossy, then mix in sour cream, vanilla, lime zest, and a small pinch of salt. Keep the speed on low to medium to avoid too much air.

Mix in eggs gently. Add eggs one at a time, mixing on low just until each disappears. Overbeating introduces air, which can cause cracks.

Stir in key lime juice. Mix on low until the batter is smooth. It will be silky and pourable but not thin.

Fill the crust. Pour the filling over the cooled crust. Tap the pan on the counter a few times to release bubbles.

Bake without a water bath. Bake at 325°F for 45–55 minutes. The edges should be set, and the center should wobble like gentle Jell-O when you nudge the pan.

Cool slowly. Turn off the oven, crack the door, and let the cheesecake rest inside for 30 minutes. Then move it to a rack to cool to room temperature.

Chill to set. Cover and refrigerate at least 6 hours, preferably overnight. This is when the texture becomes ultra-smooth.

Finish and serve. Run a thin knife around the edge, release the springform, and transfer to a platter. Top with softly whipped cream and a sprinkle of zest, then slice with a hot, dry knife.