In a large mixing bowl whisk together melted butter, eggs, buttermilk, sugar, and instant coffee until smooth.
Pour flour, cocoa powder, baking soda, baking powder and salt into the bowl. Whisk again until a smooth batter remains.
Pour batter into a greased or lined 8x8 baking pan and smooth into an even layer. Bake at 350F for 40 minutes.
Remove cake from the oven and set aside.
Immediately prepare chocolate ganache. Pour semi-sweet chocolate chips into a mixing bowl. Heat heavy cream in a sauce pan over high heat until it just starts to boil. Pour scalded cream over the chocolate chips and whisk immediately. Continue whisking until completely smooth.
Pour ganache over warm cake in the pan and smooth over top.
Allow cake to cool completely before cutting into slices.