• Preheat your oven to 180°C (356°F). Line the base of three 7" cake tins with a circle of parchment paper and spray the sides with oil spray. Or if using 6" cake tins, use four cake pans.
• Add the cacao powder, muscovado sugar, coffee, and vanilla to a medium bowl. Add ½ cup boiled water and whisk well until the mixture is smooth. Set aside to cool for 10-15 minutes.
• To make the vegan "buttermilk" add the soy milk and apple cider vinegar to a small bowl, stir and allow to sit for 10 minutes.
• In a large bowl, whisk together the olive oil and caster sugar for a minute. Add the aquafaba and whisk again. Then add the vegan yogurt and whisk again to combine. Add the vegan buttermilk mixture to the bowl and whisk until mixed. Lastly, add the cooled cocoa mixture and whisk again to combine.
• To another bowl, add dry ingredients (flour, baking powder, baking soda, and salt) and whisk together.
• Add the dry ingredients to the bowl with the wet ingredients and use a spatula to fold everything together until you have a smooth batter.
• Divide the batter into the lined cake pans and bake for 35-40 minutes. Check they are ready by inserting a skewer, it should come out clean. Allow the cakes to cool in the tins for 15-20 minutes and then carefully turn them out onto a cooling rack to cool further. Refrigerate the cakes in an airtight container until ready to use. Chilling the cakes for a few hours makes them easier to work with and decorate.

Frosting

• Meanwhile, make the vegan chocolate Swiss meringue buttercream and transfer it to a large piping bag.
• To create a 6-tiered cake, use a serrated knife to carefully cut each cake through the middle to form 2 layers. Alternatively, you can keep them as is and make a thick 3-layer cake.
• To assemble the cake, pipe a little buttercream on your turntable to secure the cake. Make sure you reserve about a third of the buttercream for the top and sides of the cake. Place the first layer of cake and follow with a layer of piped buttercream. Continue this process for the remaining layers, then pipe the sides and top with the remaining buttercream.
• Use a cake scraper to smooth out the sides and surface of the cake.

Garnish

• Melt the chocolate and pour it into a small container lined with cling film. Place in the freezer for about 15 minutes or until solid. Wearing gloves, grate the chocolate. If the block of chocolate begins to soften, place it back in the freezer to set.
• Press the grated chocolate into the sides and on top of the cake.

Storage

• This cake is best served at room temperature so I recommend making it just before or a few hours before serving. You can keep the cake out at room temperature for up to a day and after that, store it in the fridge in an airtight container if possible. Allow it to come to room temperature for at least 2 hours before serving.