For the chocolate cake:

1. Preheat the oven to 180°C (160°C fan)
2. Grease and line four 6 inch round cake tins.
3. Put the avocado into a food processor. Process until smooth and creamy.
4. Add all the remaining cake ingredients into the food processor, and blitz until creamy and smooth
5. Divide the cake batter equally into the cake tins.
6. Bake for 40-45 minutes, until a knife inserted in the middle comes out clean. Leave to cool in the cake tin.

For the caramel mocha buttercream:

1. In a large mixing bowl, cream the butter for 5 minutes.
2. Add a few spoonfuls of icing sugar, and whisk until combined. Repeat until all icing sugar is mixed in.
3. Pour in the cooled caramel coffee, and whisk until creamy and light.

For the chocolate ganache:

1. In a pan, heat the coconut milk until just boiling.
2. Pour the hot cream over the chocolate, and leave for 5 minutes.
3. Whisk the ganache together, and pour into a piping bag.

To assemble the cake:

1. Put a cake layer on a cake board, and cover with frosting. Repeat with all layers.
2. Coat the whole cake with a smooth layer of buttercream. Reserve some buttercream for topping.
3. Use a piping bag to pour the ganache over the sides and the top.
4. Fill a piping bag with remaining buttercream, and pipe swirls on top of the cake.
5. Cover the top of the cake with chocolate sprinkles, or shavings.