Sift the flour, cocoa, baking soda and powder together. Add all the dry ingredients to the bowl of a stand mixer. If your mixer bowl holds less than 5 quarts, you will need to make the One Bundt pan recipe.

Add the vanilla and oil and paddle on low speed for about 5 minutes. When done, use a rubber scrapper and clean down the sides and bottom of the bowl to make sure all the dry ingredients were mixed with the oil. Add the eggs, mix on low for 3 minutes and clean the sides and bottom of the bowl as before.

Add the buttermilk to the mixing bowl with the speed on low. Add the buttermilk in small splashes at first. Too much buttermilk too fast and the mass of batter will fling the buttermilk out of the bowl making a mess (a BIG mess, trust me) and ruin your ratios making the cake a gamble instead of a sure thing. Once all the buttermilk is added, mix on low 2 more minutes to make sure all the batter is mixed. Scrape the sides and bottom of the bowl as before. If you find any large bits of batter, mash them against the side of the bowl with the scrapper to mix them into the batter.

Scale the batter into the two Bundt pans. Place one Bundt on one sheet pan and bake at 350 degrees for about 50 minutes or until a cake tester, aka bamboo skewer, comes out clean. Remove from the oven when done, allow to rest 5 or 10 minutes to handle the pan and tip it out onto the sheet pan lined with baking paper. You may be lucky to have had the batter overflow like a volcano, but instead of making a mess outside, there can be a very yummy treat for the baker: a cone of cake inside the hollow part of the Bundt pan. That’s your treat. I never share mine.

This cake needs no icing. For reals. Powdered sugar is just fine. But, if you have to ice it, a perfectly decadent chocolate icing or cream cheese icing would be amazing. If you find those ideas simply over the top, a simple glaze of 2 cups sifted powdered sugar, a small squeeze of corn syrup and a few teaspoons of boiling water whisked together and poured on top will be just fine. Serve with some super strong coffee or Kahlua.

Whisk the egg whites and sugar together in the bowl of a stand mixer to combine them and ensure there are no dry patches of sugar.

Place the bowl over a double boiler, making certain the bottom of the bowl does not touch the water and the bowl fits tightly on the pot.  Whisk the egg whites/sugar mixture to the temperature of 161 degrees, F.

Whisk egg whites mixture with the wire whisk at high speed.  Whip at high until the temperature of the outside of the bowl feels cool to the touch.  If you have a laser thermometer, 78 degrees or less is good.

When egg whites are to the proper temperature to ensure the butter does not melt, add one chunk of butter at a time to the bowl.  Mix on medium/high speed to maintain air and incorporate the butter.  Allow each chunk of butter to be fully incorporated before the next addition.  

When you have added half the butter, stop the mixer, scrape down the sides and bottom of the bowl and continue mixing.

As you add the butter, the egg whites will appear almost soupy and you'll have a knot in your throat that you've made an error. 

All is well!

This is a normal development and by the time you get to the last bits of the butter, the icing will start to appear as it ought. 

After the last piece of butter, add the vanilla and any color you wish if you are making only one color.

Divide portions of the icing into bowls if you are coloring with two or more colors.