This is the best cappuccino cake! It has moist coffee cake layers, frosted with coffee buttercream and finished with a coffee ganache drip for the best coffee flavor.
In a large mixing bowl cream the butter and sugar together on high speed with an electric mixer until light and fluffy, 3-4 minutes. (You can also use a stand mixer fit with a paddle attachment.)
Dissolve the instant coffee into the vanilla extract in a ramekin. Then to the butter mixture add the eggs and vanilla/instant coffee mixture and mix on medium speed until smooth, 1-2 minutes. Scrape the sides and bottom of the bowl with a spatula as necessary.
1 1/2 tbsp vanilla extract, 2 tbsp instant coffee, 3 eggs, at room temperature
Add the dry ingredients and the buttermilk to the butter/coffee mixture a little at a time until it is all added, mixing on low then medium speed for each addition. Mix just until the batter is combined and smooth, scraping the sides of the bowl as necessary.
1 cup (240 ml) buttermilk, at room temperature
Pour the batter into the prepared cake pans and bake for 27-31 minutes, or until a toothpick comes out clean from the centers.
Let the cakes cool in the pans for 2 minutes, then transfer the cakes to a wire rack to completely cool.
For the Coffee Buttercream
Add the butter and salt to a large bowl and whip on high speed with an electric mixer until it's pale in color and fluffy, around 5-10 minuets. (If using a stand mixer, use the whisk attachment.)
Add the chopped white chocolate and coffee/cream mixture to a double boiler. Heat over medium heat until melted together.
4.5 oz (127 g) white chocolate bar, chopped
Assembling the Cake
STEP ONE Creating the Crumb Coat: Place the first cake layer on the rotating cake turntable. Then add a generous amount of coffee buttercream on top of the cake layer and even it out with your offset spatula, turning the cake table as you go. Place the next cake layer over top and repeat the step. Then place the final layer over the top and place small dollops of frosting on the sides of the cake and top of the cake. Even out the frosting as much as possible with your offset spatula. Then with your cake scraper, scrape the icing across the cake, turning the cake turntable as you go to make this as easy as possible. The frosting should be a thin layer for this step. It ensures the cake's final layer will be free of crumbs. Chill the cake in the fridge for 30 minutes.
STEP TWO Final Layer of Frosting: Once the cake has chilled in the fridge, remove it and apply the final coating of frosting. You may need to rewhip the frosting at this point. Apply generous dollops of frosting on the sides of the cake and the top of the cake and smooth them out with your offset spatula. Then with your cake scraper even out the frosting, turning the cake turntable as you go, to give you a smooth finish of coffee buttercream on the entire cake. Then return the cake to the fridge to chill for 30 minutes.
STEP THREE Coffee Ganache Drip: Once the cake has finished chilling, squeeze coffee ganache around the top edges of the cake. Then squeeze ganache on the top of the cake and smooth it out with an offset spatula. (I like to give it a swirl pattern by turning the cake turntable as I go.) Once the ganache drips are on the cake, pop it back in the fridge to chill for about 15 minutes, or until the ganache has set.
STEP FOUR Decorating the Cake: Rewhip if necessary and then transfer the remaining frosting to a piping bag fit with a decorative tip. Once the cake has chilled, pipe decorative swirls of frosting on top of the cake. Decorate with espresso beans and a dusting of cocoa powder. Transfer to a serving plate, then serve the cake! (It goes great with a cup of coffee!)