Preheat the oven to 325F and grease 2 8-inch round cake pans. Cut parchment to line the bottoms of the pans and grease the parchment as well.
In a medium bowl, whisk together the almond flour, coconut flour, whey protein, baking powder, and salt.
In a large bowl, beat the butter and sweetener together until light and fluffy. Beat in the eggs one at a time and scrape down the beaters and bowl as necessary. Beat in the vanilla extract
Add the dry ingredients in two additions, alternating with the almond milk. Beat until well combined.
Divide the batter between the two cake pans and spread to the edges. Smooth the tops and bake 25 minutes, or until the edges are golden and the tops are firm to the touch.
Remove and let cool in the pans, then flip out onto a wire rack. Be sure to peel off the parchment paper if it sticks to the cake layers.
Prepare a double batch of the Sugar Free Caramel Sauce but DO NOT add the additional water at the end of the recipe. Be sure to use a large saucepan (at least 3 quarts) as it will bubble up quite a bit.
Let the sauce cool down to room temperature. It should be quite thick at this point, but still pourable, and it will continue to thicken as it cools.
Place one layer of cake on a serving plate and pour about ⅓ of the caramel sauce on top. Carefully spread to the edges with an offset spatula and let sit another 10 to 15 minutes to thicken further.
Place the second layer of cake on top. Pour some of the caramel over the top, letting it drip down the sides, spreading it over the top and sides as you go. Continue until the top and sides are well covered. Alternatively, you can simply let it drip down the sides and not spread it over.
***If your caramel is too thin and is dripping too much off the sides of the cake, you can whisk in a tablespoon or two of powdered Swerve to help thicken it up. If it gets too thick, you can gently re-warm it over low heat to thin it up again.
This sugar free caramel sauce uses Bocha Sweet, a low carb pentose sweetener, for consistency. Currently Bocha Sweet is out of stock on Amazon, and their website indicates that they are having difficulty filling their orders at the moment. If you can't get Bocha Sweet, you can sub in xylitol or allulose. You can also use all Swerve Sweetener and add 2 teaspoons of Yacon syrup or molasses. Do be forewarned that using all Swerve will result in a frosting that re-crystallizes quite a bit upon cooling. It will still taste great.Also, if you can't get the new Brown Swerve, the addition of the Yacon or molasses will give you a caramel color and flavor.