Preheat oven to 350 degrees. Line an 8 x 8 inch cake pan with parchment paper
In a large mixing bowl whisk together almond flour, coconut flour, cocoa powder, baking powder, powdered Swerve, and salt until fully combined and no lumps remain. Set aside.
In a large mixer bowl combine melted butter, sour cream, eggs and vanilla extract. Carefully add dry ingredients to wet.
Beat on low 10 seconds or until dry ingredients are wet. Increase speed to medium and beat on medium for 30-40 seconds or until everything is fully combined and no dry ingredients are left in the bowl.
Scrape down sides of the bowl and push the batter into the center of the bowl.
Spoon the batter into the prepared cake pan and use a spatula to spread the batter evenly throughout the pan
Bake at 350 degrees for 20-25 minutes or until a tester comes out clean.
Let cool in the pan for at least 1 hour or until the ingredients are fully set.
After set for an hour gently turn onto a wire rack to cool completely before frosting it.