Adapted from King Arthur Baking’s Chocolate Stout Cake
Layers
2 cups Guinness beer
4 sticks unsalted butter
1 ½ cups Dutch process cocoa
4 cups all purpose flour
4 cups granulated sugar
1 tablespoon baking powder
1 ½ teaspoons salt
4 eggs at room temperature
¾ cup sour cream at room temperature
Ganache
2 ⅔ cup dark chocolate (60% cocoa)
2 cups heavy cream
1 teaspoon vanilla extract
1 recipe Italian meringue buttercream
6 ounces white chocolate cut into small pieces
Make the layers
Preheat the oven to 350° F. Line 2 8-inch cake pans that are 3 inches deep with parchment by cutting circles for the bottoms and then cutting long strips for the inside walls.
Place the beer and butter in a large heavy bottomed saucepan and heat until the butter melts. Once the butter melts, remove from heat and whisk in the cocoa powder. Whisk until smooth then set aside to cool to room temperature.
Sift the flour, sugar, baking powder, and salt into a large bowl. Whisk to combine and set aside.
In a large mixing bowl beat the eggs and sour cream. Add the beer mixture and mix until combined. On low speed mix in the flour mixture. Scrape the bowl and mix for another minute.
Divide the batter evenly between the two pans. Bake for 50 minutes or until a tester inserted in the middle comes out clean. Cool in the pans on a rack for 10 minutes then turn out the layers, remove the parchment and cool completely on the rack before frosting.
Once cooled I wrap and freeze one layer for later.
Make the ganache
Chop the chocolate into small pieces and place in a large heat proof bowl. Set aside. Heat the cream to a simmer in a heavy bottomed medium saucepan.
Pour the cream over the chocolate and stir until smooth. Stir in the vanilla.
Let cool, stirring occasionally until the ganache is spreadable.
Assemble the cake
Using a serrated knife slice one layer horizontally to form two layers. Save the half with the flat bottom for the top of the cake. Use wax paper to keep the cake plate clean as you frost the cake.
Place the slightly domed layer on a cake plate. Use the Italian meringue buttercream as a filling. Cover the top of this layer with a layer of buttercream almost as thick as the layer. Place the second half with the flat bottom up on top of the buttercream. Cover with a thin layer of buttercream if desired.
Spread the ganache over the top and sides of the cake smoothing with an offset spatula.
Decorate with white chocolate
Melt the white chocolate in the microwave. Use 60% power and at most 30 second intervals stirring after each interval. Once melted use a plastic fork to fling white chocolate decoratively over the top and down the sides of the cake.
The cake will keep at room temperature for a week.
