First create the beurre noisette, place the butter in a heavy based pan and heat it until it begins to separate and you have small brown deposits and it begins to smell nutty. Place in a heatproof bowl and leave to cool - but do not let it set.
Preheat you oven to 150C Fan/170C. Butter and flour your bundt tin, you'll need a 12 Cup or 10"/25cm tin.
Place the sugar in a bowl with the eggs and beat until combined, add the cooled beurre noisette and beat again. Add the coffee and buttermilk, and mix, you will have a wet sloppy mix, this is OK.
Mix the flour and baking powder together and sift it into the wet mix, stir until fully combined and no bits of flour can be seen.
Pour the mix into the prepared tin and bake it in the oven for 55 minutes. Test by sticking a skewer or toothpick into the cake. It should come out clean, if the toothpick has batter on it, cook the cake for another 5 mins and test again.
Leave the cake to cool in the tin before turning out on a wire rack.
To make the ganache, either chop or break the chocolate into small pieces and place it in a bowl.
Take the cream and heat it gently until it comes to a boil, pour this over the chocolate and stir until it's melted. Stir in the teaspoon of salt and the softened butter and leave the ganache to one side to cool.
Take the cake, turn it out and then spread the ganache on top using a palette knife. You want it to be a thick fudgey texture rather than a pouring consistency.
Decorate with a sprinkling of sea salt