For the cake layers
- Preheat oven to 180* C (350* F) Fan.
- Beat the butter and sugar in a mixer with the paddle attachment for at least 5 minutes, until light and fluffy.
- In the meantime, combine the cocoa powder and boiling water in a bowl.
- Whisk until completely combined and set aside to cool.
- In a separate bowl, combine the flour, baking powder and salt. Stir.
- When the butter-sugar mixture is fluffy enough, add the eggs one at a time and beat until completely incorporated.
- Add the vanilla extract and cocoa-water mixture. Beat on low speed until completely combined.
- Remove the mixer’s bowl from the stand, scrape down the sides of the bowl and mix with a spatula.
- Add the buttermilk and mix again.
- Add the flour mixture and gently fold.
- Cut out 2 sheets of parchment paper to fit in to two 22 cm cake pans. Place them on the bottom of the pans and grease with butter.
- Divide the mixture between the two cake pans. (If you don’t have 2 cake pans, bake the first half and then bake the second half to create 2 layers.)
- Bake for 35-40 minutes.
- When ready, remove from oven, turn out on to wire rack and allow to cool for 20 minutes.
For the buttercream frosting
- Beat the butter, icing sugar, cocoa powder and 2 tablespoons of the heavy cream with the paddle attachment on low speed.
- Gradually add the rest of the heavy cream and vanilla. Turn up the speed and beat for 2 minutes, until you create a light and fluffy frosting.
- Cut a sheet of parchment paper in to 3 strips and place them in a triangle on a cake platter. This will help you keep your cake platter clean.
- Place the first layer of cake over the parchment strips, smooth side up.
- Add 1/3 of the frosting over it and spread nice and smooth.
- Spread 50 g of melted chocolate couverture over the frosting.
- Cover with the second layer of cake and spread the rest of the frosting over it.
- Add the rest of the melted couverture and remove the strips of parchment.
- Decorate with chocolate wafers all the way around.
Serve a piece of the cake drizzled with melted couverture and add some mint leaves.