Preheat the oven to 170℃ (150℃ fan)/325°F/gas mark 3. Grease and line the base of three 20cm (8in) cake tins.
Melt the chocolate in a bowl over a pan of hot water. Remove from the heat and allow to cool. Place the coffee in a measuring jug and add 150ml (⅔ cup) of boiling water, stir until dissolved and allow to cool.
Beat the butter and sugar together until light and fluffy. add the eggs one at a time and beat well after each addition. Add a tablespoon of the flour if the mixture starts to curdle.
Beat in the melted chocolate. Sift the flour and baking powder into the bowl and fold in. Finally, add the cold coffee and mix well.
Divide equally between the three tins and level the top. Bake for 30-40 minutes or until springy to the touch. Allow to cool in the tins for a few minutes before turning out onto a wire rack to cool completely.
To Make the Butter Cream
Dissolve the coffee in 4 tbsp of boiling water. Beat the butter until softened then beat in the icing sugar until light and fluffy, Beat in the coffee until well combined.
To Make the chocolate shards
Melt each of the chocolates in a sperate bowl over a pan of hot water, and allow to cool.
Line a baking sheet with parchment and place spoonfuls of the different chocolates in a random pattern onto the parchment. Use a knife to swirl the chocolates together to give a marbled effect.
Tap the trap a few times on the work surface to remove any air bubbles and help spread the chocolate thinly. Pop into the refrigerator and allow to set marking into shards just before the chocolate fully hardens
Use about half the buttercream to sandwich the three layers of cake together and place on a serving plate.
Spread the remaining buttercream over the top and sides of the cake and pop into the refrigerator to chill for about 10 minutes.
Meanwhile, heat the cream until almost simmering the remove from the heat. Add the chopped chocolate and stir to form a smooth ganache.
Spread the ganache over the top of the cake and coax it towards the edge so that it begins to run in drips down the side of the cake. Chill for another 10 minutes.
Break the marbled chocolate into shards and use to decorate the cake pushing into the ganache and buttercream.
Nutrition information is approximate and is meant as a guideline only.