Preheat and prep: Heat the oven to 325°F (163°C). Line an 8x8-inch square pan with parchment, leaving overhang for easy lifting.
Make the red velvet base: In a bowl, whisk 2 cups almond flour, 2–3 tablespoons cocoa powder, 1/2 cup granulated sweetener, and a pinch of salt.
Add wet ingredients: Stir in 6 tablespoons melted butter, 1 large egg, 1 teaspoon vanilla, 1 teaspoon vinegar, and red food coloring until a soft dough forms.
Adjust coloring until the shade looks vibrant but not neon.
Press and par-bake: Press the mixture evenly into the lined pan. Bake for 10–12 minutes until just set. It will not be fully cooked—this prevents dryness later.
Make the cheesecake filling: Beat 16 ounces softened cream cheese with 1/2 cup powdered sweetener until smooth.
Add 1 large egg, 1 teaspoon vanilla, a pinch of salt, and 2 tablespoons heavy cream. Mix until creamy with no lumps.
Assemble: Pour the cheesecake mixture over the warm base. Smooth the top.
If you like a swirl, reserve a few tablespoons of the red batter before baking, dollop it on top now, and swirl with a skewer.
Bake: Return to the oven and bake for 18–24 minutes. The center should be set at the edges with a slight wobble in the middle. Avoid overbaking.
Cool and chill: Let the pan cool on a rack for 1 hour.
Then chill for at least 3 hours, preferably overnight. This firms the bars and improves the texture.
Slice and serve: Lift out using the parchment. Use a sharp knife, wiping between cuts, to slice into 16 squares.
Add optional sugar-free chocolate drizzle or a light dusting of powdered sweetener.