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Triple Chocolate Layer Cake slices open to reveal the layers
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5 from 10 votes

Triple Chocolate Layer Cake

This Triple Chocolate Layer Cake is so moist, fudgy, and packed with chocolate flavor. Ganache is used in between the layers and the whole cake gets covered in a silky chocolate Swiss meringue buttercream. It's SO decadent and is the best cake to celebrate the birthday of a chocolate lover.
Prep Time1 hour
Cook Time30 minutes
Rest & Assembly Time2 hours
Total Time3 hours 30 minutes
Course: Dessert
Cuisine: American
Servings: 12
Calories: 1129kcal

Equipment

  • Two 8-inch cake pans
  • Stand mixer with whisk and paddle attachment (or handheld mixer)
  • Piping bag and tips (optional)

Ingredients

Cake

  • 2 cups all-purpose flour 240g
  • 2 cups granulated sugar 400g
  • ¾ cup dutch-processed cocoa powder 75g
  • teaspoons baking soda
  • 1 teaspoon baking powder
  • 1 teaspoon kosher salt
  • 2 large eggs room temperature
  • 2 large egg yolks room temperature
  • ½ cup vegetable oil 3 fl oz
  • ½ cup unsalted butter melted (113g)
  • ¾ cup sour cream (full fat) room temperature (170g)
  • ¼ cup whole milk room temperature (60ml)
  • 1 cup very hot coffee or water 8 fl oz

Chocolate Ganache

  • cups heavy whipping cream 360ml
  • 12 oz bittersweet chocolate

Chocolate Swiss Meringue Buttercream

  • ¾ cup granulated sugar 150g
  • 4 large egg whites
  • ¼ teaspoon kosher salt
  • cups unsalted butter room temperature (339g)
  • 10 oz bittersweet chocolate chopped, melted & cooled

Chocolate Curls (optional)

  • ½ cup semi sweet chocolate
  • 1 tablespoon canola or vegetable oil

Instructions

Chocolate Cake

  • Preheat the oven to 350℉/177℃. Grease and parchment line two 8-inch round cake pans and set aside.
  • In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder and salt.
    2 cups all-purpose flour, 2 cups granulated sugar, ¾ cup dutch-processed cocoa powder, 1½ teaspoons baking soda, 1 teaspoon baking powder, 1 teaspoon kosher salt
  • In a separate bowl, whisk together the eggs and egg yolks, oil, butter, sour cream and milk until smooth, then add to the dry ingredients and mix until incorporated.
    2 large eggs, 2 large egg yolks, ½ cup vegetable oil, ½ cup unsalted butter, ¾ cup sour cream (full fat), ¼ cup whole milk
  • Next, add in about ⅓ of the hot coffee and quickly stir to temper the mixture. Add in the remaining coffee and mix until fully combined, careful not to over mix (or slosh it over the sides).
    1 cup very hot coffee or water
  • Divide the batter evenly between the two pans and bake on the middle rack for 30-35 minutes or until a toothpick inserted in the center comes out clean. Cool on a wire rack for 10 minutes, then remove the cakes from the pans, take off the parchment layer, and finish cooling on the racks.
  • Once cool, wrap each cake layer in plastic wrap and transfer to the fridge for an hour. This will firm up your cake which will help when it’s time to frost and assemble!

Chocolate Ganache

  • While the cake is cooling, chop the chocolate and place it in a bowl.
    12 oz bittersweet chocolate
  • Add the heavy cream to a saucepan and bring to a simmer, then pour over the chocolate. Allow it to sit for about one minute, then stir constantly from the center until the mixture is totally incorporated.
    1½ cups heavy whipping cream
  • Set it aside to cool and thicken. You'll want it to reach a spreadable consistency to go in between the cake layers and fully cover the cake.

Chocolate Swiss Meringue Buttercream

  • Chop the chocolate and melt (either in a double boiler or in the microwave - carefully) and set aside to cool.
    10 oz bittersweet chocolate
  • Add the egg whites, sugar, and salt to a bowl over a double boiler on medium high heat, whisking constantly until the sugar is dissolved, warm to the touch, and slightly foamy. You can check that the sugar is dissolved by rubbing your fingers together. If you can still feel the sugar granules, keep whisking and heating.
    ¾ cup granulated sugar, 4 large egg whites, ¼ teaspoon kosher salt
  • Transfer the egg and sugar mixture to a stand mixer fitted with the whisk attachment. Whip the whites on high speed until it reaches stiff peaks. A large ball of meringue will form in the center of the whisk and the peak will stand up on the end.
  • Once you’ve reached stiff peaks, switch to the paddle attachment and on medium speed, add 2 tablespoons of the softened butter at a time, waiting until fully incorporated before adding the next 2 tablespoons.
    1½ cups unsalted butter
  • Continue this process 2 tablespoons at a time until all of the butter is used. It may look curdled around the halfway point, but just keep whipping and it will come together. After all the butter is incorporated, add the cooled, melted chocolate and mix on low until combined.

Assembly

  • Cut off the top mounded layer of the cake (and freeze for snacks), then cut each cake evenly in half using a serrated knife. When you’re done, you’ll have 4 even discs of cake.
  • Put a quarter sized dollop of ganache onto the base of the cake stand, plate, or whatever you plan to serve it on, then add your first cake layer.
  • Add a large dollop of ganache on top of the first cake layer and spread evenly the whole way to the edges. Add the next cake layer, and repeat the steps. Once the top layer has been added, use the remaining ganache to entirely cover the cake with a thin layer. This is the crumb coat and will help to prevent any crumbs getting into the Swiss meringue buttercream.
  • Transfer the cake to the fridge for 15-30 minutes so the ganache can harden up prior to adding the buttercream.
  • Remove the cake from the fridge and add a few large dollops of buttercream to the top of the cake. Working from the middle, gently push the buttercream to the edges, then down the sides of the cake and cover all layers. You will need to continue adding buttercream until it is completely covered and you can’t see any of the chocolate ganache through the layers.
  • Smooth it out using an offset spatula or cake scraper, then use the excess buttercream to pipe decorative swirls, if you’d like.

Chocolate Curls

  • Melt together the chocolate oil in 20 second increments in the microwave, stirring between each.
    ½ cup semi sweet chocolate, 1 tablespoon canola or vegetable oil
  • Spread evenly into a very thin layer on the bottom of a clean cookie sheet and place into the freezer until solid. 
  • Remove from the freezer and let stand for about 2 minutes, the use a bench scraper at a 45 degree angle to push from the bottom to the top to create the curls.
  • If the chocolate isn't curling and just making shards, it may still be too cold, so give it another minute and try again. If it becomes too soft and just folds, return to the freezer for a few minutes.

Notes

Store the cake at room temperature for 2 days, then transfer to the fridge for another 5 days. Be sure to allow your cake (or slice) to come to room temperature before enjoying. Only cover the exposed cake pieces with plastic wrap.
Be sure you have an absolutely clean whisk, paddle, and bowl to make your meringue. Any sort of residue can prevent your egg whites from whipping appropriately.
When you set up your double boiler for the Swiss meringue, be sure not to let the water touch the bottom of bowl when you are whisking your egg whites.
For the Swiss meringue, make sure the mixing bowl is no longer warm to the touch before adding in the butter. If it is still warm, the butter will melt and the buttercream will break. If this happens, transfer the mixing bowl to the fridge for about 15 minutes, then whip again.

Nutrition

Calories: 1129kcal | Carbohydrates: 98g | Protein: 11g | Fat: 80g | Saturated Fat: 44g | Polyunsaturated Fat: 9g | Monounsaturated Fat: 22g | Trans Fat: 1g | Cholesterol: 193mg | Sodium: 480mg | Potassium: 529mg | Fiber: 7g | Sugar: 68g | Vitamin A: 1593IU | Vitamin C: 1mg | Calcium: 126mg | Iron: 6mg