Prep the pan. Line an 8x8-inch baking pan with parchment, leaving overhang for easy lifting. Preheat oven to 325°F (163°C).

Make the crust. In a bowl, mix almond flour, sweetener, salt, melted butter, vanilla, and lemon zest. Stir until the mixture looks like damp sand and clumps when pressed.

Press and par-bake. Press the crust into an even layer in the pan. Bake for 10–12 minutes, until lightly golden at the edges. Cool for at least 10 minutes.

Make the raspberry swirl. Mash raspberries with sweetener and lemon juice. If you prefer a smooth swirl, press through a fine sieve to remove seeds. Set aside.

Beat the cream cheese. In a large bowl, beat softened cream cheese with powdered sweetener until smooth and fluffy, about 1–2 minutes. Avoid over-beating to minimize air bubbles.

Add the rest of the filling. Beat in eggs one at a time just until combined. Mix in sour cream, lemon juice, lemon zest, vanilla, and a pinch of salt. The batter should be silky and pourable.

Assemble. Pour the filling over the cooled crust. Spoon small dollops of raspberry mixture across the top. Use a skewer or knife to gently swirl, making figure-eight motions. Don’t overdo it—2–3 passes are enough.

Bake. Bake at 325°F for 28–35 minutes, until the edges are set and the center has a slight jiggle. Do not bake until firm—carryover heat finishes the job.

Cool gradually. Turn off the oven, crack the door, and let the bars rest inside for 10 minutes. Then transfer to a rack and cool to room temperature.

Chill to set. Refrigerate for at least 4 hours, preferably overnight. Lift out using the parchment, slice into 12–16 bars, and garnish if you’d like.