With the pan prepared, including parchment, the rack placed in the lower third of the preheated oven, as per 'HC''s instructions, I was ready to go.
Similar to the "Chocolate Velvet Fudge Cake", I whisked the eggs with some buttermilk, the vanilla & the eggs. It stopped just short of frothing, perhaps due to the yolk's & the buttermilk. In my stand mixer I mixed the dry ingredients, on low speed, then added the butter & remaining buttermilk, just until the dry ingredients were moistened. Then to add structure the speed was increased to medium, for a minute & a half.
Scraping down the sides I used more care to include all of the ingredients. Then, using attention to the details I added the egg mixture in two batches, at med-low speed. Then gradually increasing the speed to medium, which absorb's all of the ingredients & strengthens the structure.
Pouring the batter into the prepared pan, & smoothed the top of the batter I realized this has to be the most uncomplicated cakes I'd made in awhile. But, It's not done, so I hold my tongue, and wish for as easy an ending, as the begining was.
I checked it at 30, & 35 minutes, but didn't feel it was done until 36 minutes. I followed the directions regarding cooling to a T, later transferring it to a serving plate. I noted a bit later that it seemed to have shrunken in the center just the tinest bit. Wondering if I was losing my skills, I said a quick prayer.
I'd never made a buttercream in a food processor before, & with simply measuring the ingredients, per the scale method, it honestly took longer to attach the lid to the processor, than to weigh & insert the ingredients in the container.
I only frosted the top, as done in "RHC"'s, but I couldn't help licking the spatula. Happy Baking, jo