SERVES 10 TO 12
Be sure to use cake pans with at least 2-inch-tall sides. For a smooth, spreadable frosting, use chopped semisweet chocolate, not chocolate chips—chocolate chips contain less cocoa butter than bar chocolate and will not melt as readily. As for other bar chocolate, bittersweet chocolate that is 60 percent cacao can be substituted but it will produce a stiffer, although still spreadable, frosting. Bittersweet chocolate with 70 percent cacao, however, should be avoided—it will produce a frosting that is crumbly and will not spread. For best results, do not make the frosting until the cakes are cooled, and use the frosting as soon as it is ready. If the frosting gets too cold and stiff to spread easily, wrap the mixer bowl with a dish towel soaked in hot water and mix on low speed until the frosting appears creamy and smooth. Click here for more information on splitting cake layers evenly. Click here For more information on frosting a layer cake. See the sidebars that follow the recipe.
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CAKE |
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4 |
ounces unsweetened chocolate, chopped coarse |
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¼ |
cup (¾ ounce) Dutch-processed cocoa powder |
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½ |
cup hot water |
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1¾ |
cups (12¼ ounces) sugar |
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1¾ |
cups (8¾ ounces) all-purpose flour |
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1½ |
teaspoons baking soda |
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1 |
teaspoon salt |
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1 |
cup buttermilk |
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2 |
teaspoons vanilla extract |
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4 |
large eggs plus 2 large yolks, room temperature |
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12 |
tablespoons unsalted butter, cut into 12 pieces and softened |
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FROSTING |
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1 |
pound semisweet chocolate, chopped fine |
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8 |
tablespoons unsalted butter |
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⅓ |
cup (2⅓ ounces) sugar |
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2 |
tablespoons corn syrup |
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2 |
teaspoons vanilla extract |
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¼ |
teaspoon salt |
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1¼ |
cups heavy cream, chilled |
1. FOR THE CAKE: Adjust oven rack to middle position and heat oven to 350 degrees. Grease two 9-inch round cake pans, line with parchment paper, grease parchment, and flour pans. Combine chocolate, cocoa, and hot water in medium heatproof bowl set over saucepan filled with 1 inch of barely simmering water and stir with heatproof rubber spatula until chocolate is melted, about 2 minutes. Add ½ cup sugar to chocolate mixture and stir until thick and glossy, 1 to 2 minutes. Remove bowl from heat; set aside to cool.
2. Whisk flour, baking soda, and salt together in medium bowl. Combine buttermilk and vanilla in small bowl. Using stand mixer fitted with whisk, whip eggs and yolks on medium-low speed until combined, about 10 seconds. Add remaining 1¼ cups sugar, increase speed to high, and whip until light and fluffy, 2 to 3 minutes. Replace whisk with paddle. Add cooled chocolate mixture to egg mixture and mix on medium speed until thoroughly combined, 30 to 45 seconds, scraping down bowl as needed. Add softened butter 1 piece at a time, mixing about 10 seconds after each addition. Add flour in 3 additions, alternating with buttermilk mixture in 2 additions, mixing until incorporated after each addition (about 15 seconds), scraping down bowl as needed (batter may appear curdled). Mix at medium-low speed until batter is thoroughly combined, about 15 seconds. Remove bowl from mixer and give batter final stir by hand.
3. Divide batter evenly between prepared pans and smooth tops with rubber spatula. Bake until toothpick inserted in center of cake comes out with few crumbs attached, 25 to 30 minutes, rotating pans halfway through baking. Let cakes cool in pans on wire rack for 10 minutes. Remove cakes from pans, discard parchment, and let cool completely, about 2 hours, before frosting. (Cooled cakes can be wrapped tightly in plastic wrap and kept at room temperature for up to 1 day. Wrapped tightly in plastic, then aluminum foil, cakes can be frozen for up to 1 month. Defrost cakes at room temperature before unwrapping and frosting.)
4. FOR THE FROSTING: Melt chocolate in heatproof bowl set over saucepan containing 1 inch of barely simmering water, stirring occasionally until smooth. Remove from heat and set aside. Meanwhile, melt butter in small saucepan over medium-low heat. Increase heat to medium, add sugar, corn syrup, vanilla, and salt and stir with heatproof rubber spatula until sugar is dissolved, 4 to 5 minutes. In bowl of stand mixer, combine melted chocolate, butter mixture, and cream and stir until thoroughly combined.
5. Fill large bowl halfway with ice and water, place mixer bowl over ice bath, and stir mixture constantly with rubber spatula until frosting is thick and just beginning to harden against sides of bowl, 1 to 2 minutes (frosting should be 70 degrees). Fit stand mixer with paddle and beat frosting on medium-high speed until frosting is light and fluffy, 1 to 2 minutes. Using rubber spatula, stir until completely smooth.
6. Line edges of cake platter with 4 strips of parchment paper to keep platter clean. Place 1 cake layer on prepared platter. Place about 1½ cups frosting in center of cake layer and, using large spatula, spread in even layer right to edge of cake. Place second cake layer on top, making sure layers are aligned, then frost top in same manner as first layer, this time spreading frosting until slightly over edge. Gather more frosting on tip of spatula and gently spread icing onto side of cake. Smooth frosting by gently running edge of spatula around cake and leveling ridge that forms around top edge, or create billows by pressing back of spoon into frosting and twirling spoon as you lift away. Carefully pull out pieces of parchment from beneath cake before serving. (Assembled cake can be refrigerated for up to 1 day. Bring to room temperature before serving.)