1Whisk together flour, cornflour, sugars, cocoa powder, baking powder, baking soda, and salt in a bowl.
2In another bowl, whisk buttermilk, oil, eggs, and vanilla until smooth. Then whisk in the coffee.
3Make a well in the dry ingredients and pour the wet batter into the dry. Mix until combined.
4Pour the batter evenly into two greased 9 inch cake pans.
5Bake at 180 for 35 mins
6Make the ganache by adding heavy cream and sugar to a saucepan over medium heat. Bring to a simmer, remove from heat and pour into a bowl with chocolate and butter. Whisk until smooth and refrigerate for at least 30 mins.