01 -
Preheat your oven to 180ºC / 160ºC fan and line two 8-inch cake tins with baking parchment. Beat butter and sugar together until light and fluffy.
02 -
Add self-raising flour and eggs to the mixture and blend until incorporated. Divide the batter evenly between two bowls.
03 -
Mix cocoa powder and milk into one bowl, and vanilla extract into the other. Mix each bowl thoroughly.
04 -
Dollop the two batters alternately into the prepared tins and swirl gently with a skewer or knife to create a marbled effect.
05 -
Bake in the preheated oven for 30-35 minutes, or until a skewer inserted in the center comes out clean. Allow the cakes to cool completely.
06 -
Whip the room-temperature butter for a few minutes to aerate. Gradually add icing sugar and beat until light.
07 -
Split the buttercream into two bowls. Add cocoa powder to one bowl, and vanilla extract to the other. Mix each thoroughly.
08 -
Lay a large piece of cling film flat. Place the two buttercream flavors in lines down the center. Roll into a sausage shape, snip the end, and insert into a piping bag.
09 -
Pipe the buttercream onto the cooled cakes in your desired pattern. Decorate with sprinkles as a finishing touch.