- 3/4 cup unsalted butter, room temperature
- 3/4 cup caster (fine) sugar
- 1 teaspoon vanilla extract
- 1 egg
- 1/4 cup buttermilk
- 2 cups plain flour
- 1/2 cup cocoa powder
- 1/4 cup milk
- 1/2 cup smooth peanut butter
- 5 3/4 tablespoon powdered sugar
- 2 3/4 tablespoon unsalted butter, softened
- Beat the butter and sugar together until light and fluffy, about 3 minutes.
- Add the vanilla extract and the egg and beat again. Next, add the buttermilk and beat again to combine. Sift in the remaining dry ingredients, alternating with the milk, finishing with the dry.
- Add the mixture to a piping bag and pipe large mounds of dough onto a baking sheet. Smooth any bumpy edges with a slightly wet finger.
- Bake at 180°C/350°F for 12-13 minutes. Allow to cool on a wire rack.
- To finish, spoon the mixture onto one side of the cooled cakes and sandwich another cake on top.
- Beat the peanut butter, powdered sugar and butter together until they are combined and smooth. Set aside.