Heat the oven to 180°C/160°C fan/Gas Mark 4. Grease 3 x 15cm round tins butter then base line with nonstick baking paper. Place the cocoa powder in a large bowl and mix with 100ml hot water. Add the eggs, oil and butter and mix until well combined. In a separate bowl sieve the sugar, flour and baking powder. Pour over the chocolate mixture and using an electric mix beat together for a minute. Divide between the 3 tins and transfer to the oven to bake for 20 minutes until risen and a skewer comes out clean. Place the marmalade in a bowl with 1 tbsp hot water. Heat in the microwave for 45 seconds. Brush over the warm cakes then leave to cool in their tins for 10 minutes before turning out onto a wire rack to cool completely. Meanwhile pour the cream into a saucepan and bring just to the boil. Remove from the heat and add the chocolate, cover with a lid and leave for 5 minutes to melt. Then mix until combined, recover with the lid and leave to thicken slightly. To make the butter cream beat the butter and icing sugar together until pale and fluffy. Add the marmalade and beat until combined. Place a tray under a wire rack. Spread half of the buttercream over one sponge layer, top with another sponge layer and spread over the remaining butter cream then finish with the remaining sponge. Pour over the chocolate ganache covering the sides well, spread evenly with a palette knife. Leave to set slightly. Spoon the remaining ganache into a piping bag and pipe simple swirls or flowers to decorate. Tip If you are not handy with a palette knife don't leave the chocolate to thicken too much. You will then be able to pour the ganache over the cake and it will drip down the sides naturally.