Makes two 9-inch cakes or 24 cupcakes
- 1 1/2 cups cake flour
- 1 1/2 cups sugar, plus more for unmolding the cakes
- 1/2 cup (1 stick) unsalted butter, softened at room temperature
- 1/3 cup unsweetened Dutch-process cocoa powder
- 1 tsp. baking soda
- 1/4 tsp. baking powder
- 1/3 cup melted unsweetened chocolate (such as Baker's)
- 1/2 cup hot water
- 2 extra-large eggs
- 1/2 cup buttermilk
- Position a rack in the center of the oven, and preheat to 350 F (360 F for cupcakes)
- Put flour, sugar, butter, cocoa, baking soda, and baking powder in the bowl of a stand mixer fitted with the paddle attachment. Mix on low speed just until the ingredients are blended together, a few seconds, then raise the speed to low-medium and continue to mix until smooth, approximately 1 additional minute.
- Stop the mixer and pour in the chocolate. Mix for 1 minute on low speed. With the mixer on, pour in the hot water. Add the eggs, one egg at a time, adding the next one after the previous one has been absorbed. With the mixer still running, pour in the buttermilk. Stop periodically and scrape from the bottom with a rubber spatula to be sure all the ingredients are fully integrated, and return the mixer to low-medium speed. Continue to mix for 1 additional minute to ensure the eggs are full absorbed. Before baking, be sure the batter is between 70 and 73 degrees, or the cake will crown.
- Grease two 9-inch cake pans (2 inch deep) and flour them.
- Divide the batter evenly between the two cake pans, using a rubber spatula to scrape down the bowl and get as much batter as possible out.
- Bake until the cakes begin to pull from the sides of the pan and are springy to the touch, 25 to 30 mins.
- Remove from the oven and let cool for at least 30 minutes, preferable 1 hour. The cakes should be at room temperature before you remove them from the pan. Put a piece of parchment paper on a cookie sheet, sprinkle with sugar, and turn the cakes out onto parchment; the sugar will keep them from sticking.