Preheat oven to 180°C / 350°F. Grease three 8-inch springform cake pans and set aside.

In a large bowl, whisk together 1 1/2 cups sifted coconut flour, 1 1/2 cups arrowroot flour, 1 tablespoon baking soda, 1 tablespoon baking powder, and 1/2 teaspoon salt until evenly combined.

In a separate large bowl, combine 2/3 cup melted coconut oil, 1 1/2 cups maple syrup (or honey), and 1 1/2 cups cocoa powder. Whisk until the mixture is smooth and glossy.

Add the 6 large eggs to the wet mixture one at a time, whisking after each egg until fully incorporated. Then whisk in 1 1/2 cups milk (I used unsweetened almond milk) and 1 tablespoon vanilla extract until combined.

Add the dry ingredients to the wet ingredients and gently fold with a spatula until fully combined. The batter will be thick and dense.

Divide the batter evenly among the three prepared cake pans and smooth the tops.

Bake for 27–30 minutes, or until a skewer inserted into the centers comes out mostly clean (a few moist crumbs are fine).

Remove the pans from the oven and let the cakes cool in the pans for about 10 minutes. Then release the springform sides and transfer the cake layers to a wire rack to cool completely.

To assemble, place one cooled layer on a serving plate and spread with chocolate frosting (use from the 1–2 cups chocolate frosting). Add the second layer, spread more frosting, then add the final layer. Use the remaining frosting to cover the top and exterior of the cake.

Let the assembled cake sit about 20 minutes to allow the frosting to set before slicing and serving.