Preheat your oven to 350 F degrees. Lightly coat two 8-inch round cake pans or three 6-inch cake pans with nonstick baking spray and line the bottom with parchment paper rounds. Set aside.
Add almond milk and apple cider vinegar to a large measuring cup. Set aside and allow to sit (and curdle) for 5 minutes while you mix the other ingredients.
Meanwhile, in a separate large mixing bowl, add the almond flour, coconut flour, cocoa powder, espresso powder, sweetener, baking powder, baking soda and salt and whisk to combine.
Add the beaten eggs, coconut oil, and vanilla extract. Pour in the curdled milk and mix until thoroughly combined.
Divide the batter evenly between the two baking pans and bake in preheated oven for 18-25 minutes (rotating pan halfway through), or until a toothpick comes out clean. Do NOT overbake - the time will vary depending on your oven.
Allow the cakes to cool completely in the pan (or at least 30 minutes) before removing from the pan or it may (will) fall apart. Remove the parchment paper liner. Cool completely before frosting.