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

Make the raspberry swirl: In a small saucepan, combine raspberries, powdered sweetener, and a squeeze of lemon. Simmer 5–7 minutes, smashing berries until saucy. If you want it thicker, stir in a pinch of chia seeds and let it cool. Set aside to cool to room temperature.

Mix the crust: Stir almond flour, cocoa powder, granulated sweetener, salt, melted butter, and vanilla until it resembles damp sand. Press evenly into the lined pan. Bake 8–10 minutes, then let it cool slightly.

Melt the chocolate: Gently melt dark chocolate in short bursts in the microwave or over a double boiler. Let it cool to lukewarm so it doesn’t seize your batter.

Beat the filling base: In a mixing bowl, beat softened cream cheese and sweetener until smooth and fluffy, scraping the bowl as needed. Add sour cream, heavy cream, vanilla, and a pinch of salt. Mix just until combined.

Add eggs and chocolate: Beat in eggs one at a time on low speed. Sift in cocoa powder. Stream in the melted chocolate and mix on low until glossy and uniform. Avoid overmixing to prevent excess air.

Assemble: Pour the chocolate cheesecake batter over the cooled crust and smooth the top. Dollop small spoonfuls of the raspberry sauce across the surface, then drag a skewer or knife to create swirls. Don’t over-swirl.

Bake: Bake at 325°F for 28–35 minutes. The center should be slightly jiggly, and the edges set. If the top starts to darken, tent lightly with foil.

Cool and chill: Let the pan cool on a rack until room temperature. Refrigerate at least 4 hours (overnight is best) until fully set.

Slice and serve: Use the parchment to lift the slab out. Warm a knife under hot water, wipe dry, and slice into bars. Garnish with fresh raspberries or shaved chocolate if you like.