Preheat oven to 150 degree C. Line the base and sides of a 20 cm deep round pan with parchment paper. Make sure the parchment comes above the pan, since it will rise so much.
Now time to make the batter. Take water in a sauce pan, Add in coffee, butter, dark chocolate and heat it gently till it is melted. Add in sugar and whisk well till it is completely melted. Pour this in a bowl and set aside to cool down a bit.
Now sieve flour, cocoa, baking soda, baking powder and salt. Set aside.
Now add in milk to the cooled chocolate mix, along with oil. Add in one egg at a time and whisk it well. Add in the sifted flour mix in and mix well to a smooth batter.
Pour this in the prepared pan and pop it in oven for 1.45 hours to 2 hours. Now remove it from oven and let it cool completely.
Now un mould from tin and cut the top with a serrated knife. Spoon the ganache on top and spread on all sides. Decorate as you wish. Chill in fridge for couple of hours. Serve.