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

Make the crust: In a bowl, mix almond flour, sweetener, salt, melted butter, and vanilla until the mixture feels like damp sand. Press it evenly into the pan, going slightly up the sides. Bake for 10–12 minutes until lightly golden. Cool while you make the filling.

Cook the raspberry swirl: In a small saucepan, combine raspberries, sweetener, and lemon juice. Cook over medium heat for 4–5 minutes, mashing the berries until saucy. Taste and adjust sweetness. Strain to remove seeds if you like a smoother swirl. Cool to room temp.

Beat the filling: With a hand or stand mixer on medium-low, beat cream cheese until completely smooth, about 2 minutes. Add sweetener and salt; beat until fluffy, scraping the bowl. Mix in sour cream, vanilla, and lemon zest.

Add the eggs: Beat in eggs one at a time on low speed until just combined. Don’t overmix; too much air can cause cracks.

Assemble: Pour the filling over the cooled crust. Dollop teaspoons of raspberry sauce across the top. Use a skewer or knife to swirl gently, staying near the surface so the swirl doesn’t sink.

Prepare a water bath (optional but helpful): Wrap the outside of the springform pan in two layers of foil. Set it in a larger roasting pan and pour hot water halfway up the sides. This helps prevent cracks.

Bake: Bake at 325°F for 45–55 minutes. The edges should be set and the center should still wobble slightly when you nudge the pan.

Cool slowly: Turn off the oven, crack the door, and let the cheesecake rest inside for 45–60 minutes. Then remove from the oven and water bath.

Chill: Run a thin knife around the edge to loosen. Cool to room temperature, then cover and refrigerate at least 6 hours, preferably overnight.

Serve: Release the springform ring, slice with a hot, clean knife, and top with fresh raspberries or a light swirl of whipped cream if you like.