• In a small bowl, add boiling water to cocoa and stir.
• In your kitchen mixer or in a medium-size bowl, combine butter and sugar and beat at a high speed for 7 minutes.
• Add vanilla essence.
• Add eggs one by one and mix for another 7-10 minutes on high speed.
• Fold in the flour and baking powder gently, and mix on medium speed.
• Once all the flour has been incorporated, add buttermilk and cocoa and continue to mix.
• Transfer to springform pan and bake for 40 minutes.
• When a skewer is inserted in the middle of the cake it should come out clean.
• If the cake dips a little in the middle, don't worry, you're going to invert the cake and cover it with chocolate ganache.

To prepare cake for ganache

• After removing from the oven, allow to rest and cool at least one hour.
• In the meanwhile, cut out 4 large square pieces of parchment paper.
• Once the cake is cool, place parchment paper squares on top of cake- make sure they are slightly overlapping when placed on the cake. Take the cake dish / stand in which you will serve the cake and with a swift movement, invert the cake onto it.
• Leave the parchment paper as is, you will need it when you decorate it with the ganache.

Ganache

• Warm 240 ml heavy whipping cream till scalding, but it should not boil over. Pour over 200g dark chocolate (I use Valrhona Guanaja). Allow it to rest for a bit, if you start whipping it immediately, bubbles will form.
• Stir gently and slowly. Please do not whip rigorously- it will create pockets of air and you won't have a smooth, shiny ganache in the end.
• Add a good pinch of fleur de sel, do a taste test. Add more if you like. I added a mere pinch.
• Give the ganache a gentle stir.

Final Assembly

• With a spatula, apply the soft ganache over the cake in gentle swirls. (You will have some ganache leftover, serve with the cake in a small bowl).
• When spreading the ganache on the cake, there will be overflow on the sides, but don't worry, that is what the parchment paper is there for.
• Place cake in fridge and allow to rest for at least half an hour.
• Remove from fridge and gently pull the parchment squares out from under the cake.
• Serve with a light sprinkling of fleur de sel.