Use the butter to line the cake tin, preheat the oven to 180ºC/gas mark 4/350ºF. Break 250G of dark chocolate into pieces and into the cooking pan, add the butter in and stir on a low heat frequently. Mix a heaped tsp of coffee granules in while adding a small amount of water. Wait for everything to melt.
Once the chocolate and butter has melted, mix in 300G of plain flour, 200G of caster sugar and 100G of sugar. Add in the cocoa powder and mix well. Beat 3 eggs in the bowl while slowly adding 60ml of buttermilk and a dollop of nutella!
Add the Egg, buttermilk and nutella mixture into the chocolate and flour mix and stir very well until all lumps are gone. The consistency should be smooth and flowing. Pour the contents into the buttered cake tin and bake for 90 minutes. Once done prod a thin knife through the middle, if it comes out clean it's ready. Let it cool in the tin.
Add 160G of dark chocolate broke into pieces into a bowl, pour about 200Mil of double cream into the bowl while adding golden syrup and a small amount of vanilla extract, heat until liquid.
Drizzle the ganache over the cooled cake and smooth it over with a blunt knife. Enjoy!