DARK-CHOCOLATE CAKE WITH GANACHE FROSTING

Steps:

• Preheat oven to 350 degrees. Butter two 8-inch round cake pans; dust with cocoa, tapping out excess. Line bottom of each pan with a round of parchment paper; set aside. In a medium bowl, whisk together flour, cocoa, baking powder, baking soda, and salt; set aside.
• In a large bowl, using an electric mixer, beat butter and sugar until light and fluffy. Add eggs and yolks, one at a time, beating well after each addition; beat in chocolate and vanilla. With mixer on low, alternately add flour mixture in three parts and buttermilk in two, beginning and ending with flour mixture.
• Divide batter between prepared pans; smooth tops. Bake until a toothpick inserted in center of a cake comes out clean, 40 to 45 minutes. Cool in pans 15 minutes; run a knife around edge of each pan, and invert cakes onto a wire rack to cool completely.
• Set a rimmed baking sheet upside down on a work surface. Place one cake on sheet, and spread top with 1/3 of ganache. Place second cake on top, and spread remaining ganache over top and sides of cake. Using two wide metal spatulas, carefully transfer frosted cake to a serving platter.