A rich chocolate cake is balanced by a light vanilla buttercream in this simple and elegant naked cake.
Heat oven to 350°F. Grease, and flour 2, 9 inch round cake pans.
Chop chocolate into fine pieces. Place in a metal bowl over gentle simmering water. Add in the cocoa powder, and hot water. Stir often, until the chocolate is melted and the mixture is combined. Add in a ½ cup of the sugar to the mixture and stir until the sugar is incorporated and glossy. Remove from heat and allow to cool.
In a separate bowl, combine the flour, baking soda, and salt.
Combine the buttermilk and vanilla in a measuring cup.
In a large bowl or stand mixer with a paddle attachment, beat the eggs and yolks on high for 1 minute. Add remaining 1 ¼ cup sugar and beat on high for 2 minutes until light and fluffy. Add the cooled chocolate mixture to the eggs, mix at a medium speed until combined. Add the butter, one piece at a time. Allow to mix for about 10 seconds before adding the next piece. Scrape down the sides of the bowl often.
On low speed, alternate adding in the flour and the buttermilk, starting and ending with the flour. (Add in a ⅓ of the dry ingredients, mix until almost completely combined, then add half of the buttermilk mixture. Repeat process once more. Then add the remaining flour.) Beat until well combined.
Divide the batter evenly between the two pans. Smooth out the batter to make even. Bake on a center rack for 25-30 minutes, or until the cake slightly springs back when touched and a toothpick comes out clean.
For the Frosting:
In a large bowl or stand mixer, whisk butter until light and creamy, for about 7 minutes, on a high speed.
At a medium speed, slowly add in the powdered sugar one tablespoon at a time. Make sure the sugar has mixed completely in before adding next tablespoon. Scrape the bowl often. Add in the vanilla, milk, and salt. Whisk on high for 4 more minutes until very creamy and fluffy.
Place 2 cups on top on one of the cooled cakes. Evenly spread to edges and place second cake on top. Use remaining 1 ½ cups to cover the top and sides of the cake.
Remove from oven and let rest in pan for 10 minutes. Remove the cakes from the pans and let rest on wire racks until completely cooled.
Recipe inspired by: https://www.cookiemadness.net/2015/11/old-fashioned-chocolate-layer-cake/