Step 1

Preheat the oven to Grease two round 8" or 9" cake pans with coconut oil or butter, or spray them with baking spray. Line the bottoms with parchment paper, grease again lightly and sprinkle with cocoa powder to coat the inside. Tap out the excess and set aside.

Step 2

In a large bowl, sift together the brown rice flour, potato starch and tapioca flour and make sure everything is well mixed. Measure out 2 1/2 cups of this mixture to use in the recipe and save the rest for another use.

Step 3

In a large bowl or in a stand mixer, add the flour blend you made, sugar, baking soda, baking powder, xanthan gum and salt. Whisk or mix together to combine.

Step 4

In a 4-cup measuring cup or a medium size bowl, measure in the buttermilk and water. Add the egg, oil and vanilla and whisk to break up the egg.

Step 5

Add the buttermilk mixture to the flour mixture and blend with a hand mixer, whisk or in your stand mixer until no lumps of flour remain.

Step 6

Divide the batter between the two pans and bake on the center rack, rotating half way through, until a toothpick comes out clean--25 to 30 minutes. Don't overbake your cakes or they will be dry. Start checking them 5 to 7 minutes before the end of the baking cycle. If you use 8" pans your cakes may take closer to 40 minutes to bake.

Step 7

Once baked, let cool in the pans 5 minutes then turn out on a wire rack to finish cooling completely.

Step 8

Add the chocolate chips to a microwave safe bowl and heat in 30 second increments, stirring in between until the chocolate chips melt. About a minute and 30 seconds should do it. Set aside to cool completely.

Step 9

Mix the cocoa in the boiling water and stir to combine. It will thicken. Set aside to cool completely.

Step 10

In a medium bowl, beat the butter, sugar, milk and salt on high with a hand mixer or in a stand mixer until the sugar dissolves and the mixture becomes almost white and fluffy. About 7 minutes. No less.

Step 11

If the chocolate and cocoa mixtures are cool, add to the butter mixture and beat until everything is incorporated. If your chocolate is warm you'll melt the butter and ruin the frosting so make sure it's room temperature.

Step 12

Frost the cakes once they are room temperature. The frosting will firm as it sets and will be quite hard if refrigerated. Best if served the day it's made but will be delicious the next day as well.