Chocolate Layer Cake with Swiss Buttercream and Ganache

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  • Level: Intermediate
  • Total: 2 hr 30 min (plus cooling)
  • Active: 1 hr 20 min
  • Yield: 12 to 16 servings
This cake recipe combines two of our favorite elements in one: a moist, tender and rich chocolate layer cake and silky-smooth vanilla-flavored Swiss buttercream. To make your cake really standout, spoon a decadent chocolate ganache over top until it just drips down the sides. When the ganache sets, you get a bite of each element in one — it’s pure chocolate cake decadence!


For the Cake:

For the Frosting:

For the Ganache:


  1. Make the cake: Preheat the oven to 350˚ F. Butter and flour two 9-inch round cake pans and line the bottoms with parchment paper. Put the cocoa powder and chocolate in a medium bowl. Add the boiling water and whisk until the chocolate is melted. Whisk in the sour cream until smooth; let cool to room temperature.
  2. Whisk the flour, baking soda and salt in a medium bowl; set aside. Beat the butter, granulated sugar and brown sugar in a large bowl with a mixer on medium-high speed until fluffy, 3 to 4 minutes. Add the eggs, one at a time, then the vanilla, beating well after each addition. Reduce the mixer speed to low. Beat in the flour mixture in 3 additions, alternating with the cocoa mixture in 2 additions. Finish mixing gently with a rubber spatula, scraping the bottom and sides of the bowl.
  3. Divide the batter evenly between the cake pans. Tap the pans against the counter to eliminate any air bubbles. Bake until the cakes spring back in the center when gently pressed, 35 to 40 minutes. Let the cakes cool in the pans for 10 minutes, then run an offset spatula around the edges and turn out the cakes onto a rack to cool completely. Remove the parchment.
  4. Make the frosting: Bring a few inches of water to a simmer in a medium saucepan over medium heat. Whisk the egg whites, granulated sugar and salt in the bowl of a stand mixer. Set the bowl over the saucepan (do not let the bottom of the bowl touch the water); cook, whisking, until the sugar dissolves, the egg whites are frothy and the mixture is warm, 3 to 5 minutes.
  5. Transfer the bowl to the stand mixer and beat with the whisk attachment on medium-high speed until stiff glossy peaks form and the mixture cools to room temperature, about 5 minutes. With the mixer running, add the butter a few pieces at a time, waiting for them to incorporate before adding more. (The mixture will become liquidy, then it will get thick and shiny once the butter emulsifies. It may also look curdled as you add the butter. It’s OK: Keep adding butter and beating.) Add the vanilla and beat until combined and fluffy, 3 to 5 more minutes.
  6. Cut each cake in half horizontally to create 4 layers. Place 1 layer on a cake stand or serving plate. Spread about 2/3 cup frosting on top, then repeat with the remaining cake layers, spreading more frosting in between them. Spread a thin layer of frosting on the top and sides of the cake (this is the crumb coat — it doesn’t have to be perfect), then refrigerate until the frosting sets, about 30 minutes. Spread the remaining frosting all over the top and sides of the cake, smoothing it with a bench scraper.
  7. Make the ganache: Heat the heavy cream in a saucepan over medium-high heat until steaming, then pour over the chocolate in a small heatproof bowl. Let sit for 5 minutes, then stir until smooth. Set aside until cool but still pourable, 20 to 40 minutes (the time will vary depending on the temperature and bowl). Pour the ganache on top of the cake and spread with a small offset spatula, letting it drip down the sides. Let the ganache set 20 to 30 minutes before slicing.