This sprinkle fault line cake is made with soft layers of dark chocolate cake and creamy vanilla buttercream.
Preheat oven to 350 °F. Spray three 6-inch round cake pans or two 8-inch round cake pans with non-stick spray, line the bottom of each pan with parchment paper and spray again. Set aside.
In the stand mixer bowl fitted with a paddle attachment, stir together the all-purpose flour, granulated sugar, dark cocoa powder, baking soda, and salt. Set aside.
Add the eggs and the vegetable oil on low until well incorporated.
Pour in the buttermilk and add brewed coffee. Mix on medium for 30 seconds. Scrape down the sides of the bowl.
Evenly distribute the cake batter among the three cake pans and bake for about 35-40 minutes or until a toothpick inserted into the center of each cake comes out clean or with just a few moist crumbs.
Remove cakes from oven and let cool in pans for 10 minutes before inverting onto cooling racks to cool completely — wrap cakes in plastic wrap and place in the freezer to chill for 30 minutes.
In the stand mixer bowl fitted with the paddle attachment, beat the butter until light and fluffy, about 5 minutes.
Turn the mixer to low and gradually add the powdered sugar, followed by the heavy cream, salt and vanilla extract. Mix until incorporated completely. Scrape down sides of the bowl.
Add a drop of sky blue gel food color to make the buttercream a medium blue color. Turn the mixer to medium-high and beat the frosting for about 5 minutes until light and fluffy.
Turn the mixer on low and mix for 2 minutes to push out any air bubbles.
Remove the cake layers from the freezer and unwrap the cake layers. Next, use a serrated knife to cut off the dome of the cakes to make the layers flat and even.
Add a small amount of buttercream onto the center of the cake board.
Layer the chilled dark chocolate cake, cut side up onto the cake board.
Place 1/3 of buttercream on top of the cake and add a layer of sprinkles over the buttercream.
Place another cake layer cut side down over the top. Repeat the process for another layer — Crumb coat and freeze for 20 minutes.
Add a layer of buttercream to the middle of the cake.
Then place the cake in the middle of a baking sheet pan to add a layer of sprinkles to the middle part of the cake. At this time, do not add any big sprinkles that could stick out and make it harder for frosting. Place the cake back into the freezer to set for 20 minutes.
With smooth buttercream add a thick layer to the top and bottom of the cake with an offset spatula while keeping the middle with the sprinkles exposed. Add buttercream that goes over the top edge for the rustic look.
Use a cake scraper to smooth the sides of the buttercream. Place the cake into the freezer to set the buttercream for 10 minutes.
Then mix 1/2 tsp of gold highlighter luster dust and one drop of clear alcohol (lemon extract) until it looks like paint. Then with a small brush, paint the edges of the rough buttercream edges.