Preheat oven to 350 degrees. Line bottom of loaf pan with a strip of parchment paper. 

In the bowl of your mixer (or in regular bowl) add cocoa, gluten-free flour, baking soda, espresso powder, sugar and salt. Mix together until all ingredients are well blended. 

In a separate small bowl, combine mayonnaise, egg, vanilla and water. Whisk ingredients together, then add to dry ingredients. Whisk together until all ingredients are thoroughly moistened. 

Pour batter into parchment lined loaf pan and bake for 20-30 minutes. (I will admit that I forgot how long I baked it for. I say check it after 20 minutes with a toothpick and go from there. I'm pretty sure I baked it for 30 minutes.) After removing pan from oven, allow to cool in pan for 5 minutes. Then transfer to a baking rack. Cool completely, slice down the middle and freeze for 30 minutes to an hour. 

After cake has completely frozen, make the mocha buttercream frosting. Make sure your coconut oil is soft, but not melted. Add coconut oil and shortening to clean bowl in your stand mixer. Cream oil and shortening for 1 minute until smooth and creamy. 

Sift powdered sugar into a separate bowl, making sure there are no large lumps. Add espresso powder to powdered sugar and then add both to the creamed coconut oil and shortening. Turn mixer and slowly start to whip together. As sugar and oils are mixing, add a drop of vanilla paste, then add almond milk, one tbsp at a time. Once all ingredients are together, whip frosting for 3 minutes on medium speed until fluffy. 

Remove cake layers from freezer and spread mocha buttercream frosting on bottom layer of cake. Place remaining layer on top, wrap the whole thing in plastic wrap, and return to freezer to chill prior to topping with ganache.