Step 1

For the cake: Heat your oven to 350 degrees F and lightly grease two 9-inch round cake pans with nonstick cooking spray. Line the bottom of each pan with a circle of parchment paper and set aside.

Step 2

Sift together the flour, granulated sugar, cocoa powder, baking powder, baking soda and salt in a large bowl. Whisk well to combine and set aside.

Step 3

Whisk together the buttermilk, oil, vanilla, instant espresso powder and eggs in a separate bowl. Add about a third of the dry ingredients to this wet mixture, mixing until almost combined then stir in half of the stout. Continue with another third of the dry ingredients, the remaining stout, and the remaining dry ingredients, mixing after each addition. Alternatively, you can mix everything all at once, but it might be a bit tricky to get the mixture going.

Step 4

Divide the batter between the prepared pans and bake until the center of the cakes are set and springy or a toothpick inserted into the middle comes out clean, 30 to 35 minutes. Allow the cakes to cool in their pans for at least 20 minutes before turning out onto a wire rack and cooling completely to room temperature.

Step 5

For the buttercream: Meanwhile, beat together the butter and cream cheese using a hand or stand mixer on medium speed, scraping down the bowl a few times to evenly combine. With your mixer on low, beat in the confectioners’ sugar about 1 cup at a time until smooth and creamy, scraping the bowl after each addition. Add the salt and vanilla, turn the mixer up to high and beat for 1 minute. Beat in 4 tablespoons of the cream or Irish cream, adding more cream or confectioners’ sugar if needed to reach a thick, spreadable consistency.

Step 6

Place one of the cooled cakes flat side down onto a cake pedestal or plate and top with a thick layer of the buttercream. If you’d like to add any additional fillings, scatter or drizzle over the buttercream. Place the second cake flat side up and spread the remaining frosting evenly over the top and sides of the cake.