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Guinness Chocolate Cake with Irish Buttercream

Guinness Chocolate Cake with Irish Buttercream features an easy, fudgy, and moist cocoa cake with Guinness beer and thick creamy and sweet Irish cream buttercream. The perfect St. Patrick’s Day cake! Download my FREE Best Buttercream Guide here!

Course Dessert
Cuisine American
Prep Time: 45 minutes
Cook Time: 40 minutes
Total Time: 1 hour 25 minutes
Yields: 10 servings
Recipe by Tessa Arias

Ingredients

For the Guinness Chocolate cake:

  • 1 3/4 cups (222 grams) all-purpose flour
  • 2 cups (400 grams) granulated sugar
  • 3/4 cup (64 grams) unsweetened cocoa powder
  • 2 teaspoons baking soda
  • 1/2 teaspoon baking powder
  • 1 teaspoon fine salt
  • 3/4 cup (170 grams) sour cream or plain full fat yogurt
  • 1/2 cup fresh vegetable oil
  • 3 large eggs, at room temperature
  • 1 teaspoon vanilla
  • 1 cup Guinness beer

For the Irish Buttercream:

  • 4 sticks (454 grams) unsalted butter, at room temperature
  • 6 cups (750 grams) powdered sugar, sifted
  • 1/4 cup plus 2 tablespoons Irish cream, such as Bailey’s

For the chocolate drip:

  • 4 ounces (113 grams) semisweet or bittersweet chocolate, finely chopped
  • 1/2 cup heavy cream

Directions

Make the cake:

  1. Preheat the oven to 350°F. Generously grease two 8-inch cake pans and line with parchment rounds.
  2. In a large mixing bowl, whisk together the flour, sugar, cocoa, baking soda, baking powder, and salt.
  3. In a medium bowl whisk together the sour cream, vegetable oil, eggs, vanilla, and beer.
  4. Add the wet ingredients into the dry ingredients and stir with a spatula until just combined.
  5. Divide the batter between the prepared pans and bake for 35 to 40 minutes, or until a cake tester comes out clean. Cool the cakes in their pans for 30 minutes before carefully turning them out onto a cooling rack to cool completely. If possible, freeze the cakes while you prepare the buttercream.

Make the buttercream:

  1. In a large bowl, use an electric mixer to beat the butter until light and fluffy. Gradually add the powdered sugar then the Irish cream. Beat the mixture on high speed until very light, fluffy, and smooth, about 3 minutes. If the frosting is too thick, add a splash more Irish cream. If it’s too thin, add some more powdered sugar.
  2. Assemble:
  3. Place one cake layer a cake stand or serving plate. Frost the top of the cake generously, as this will become the filling. Use even more if you're decorating as a 'naked' cake as shown in the photos. Top with the other cake layer, flat side up.

  4. With an offset spatula, spread a very thin layer of frosting all over the cake. This layer is a crumb coat and should act like spackle. For the smoothest frosting, return the cake to the fridge or freezer until firm to the touch. 
  5. Spread the remaining frosting all over the cake. If desired, focus the frosting on the top to maintain the 'naked' look. Refrigerate while you prepare chocolate drip.

Make chocolate drip:

  1. Place the chopped chocolate in a heatproof bowl. Bring the heavy cream to a simmer then immediately remove from heat and pour over chocolate. You can also do this in the microwave. Cover for a few minutes then stir until smooth.
  2. Allow to cool until it has thickened but is still pourable, about 10 minutes. Don’t place ganache in the fridge to cool. Test the consistency of the drip by pouring down the side of a glass. If it’s too thick, microwave for 5 to 10 seconds. If it’s too thin, allow to continue to cool.
  3. The cake can be stored, covered, at room temperature for up to 1 day or in the fridge for up to 3 days.