Combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt into a bowl. Stir together with a whisk until evenly combined
Add the vanilla, eggs, buttermilk, and oil and stir until combined
Once combined, add the hot coffee. Stir quickly to ensure the hot coffee is evenly distributed. The batter will be very thin
Pour the batter into a greased and floured 9x13" pan and cook for ~20 minutes (if using a sheet pan) on 350 F - make sure a toothpick comes out clean
Set aside to cool
Whipped Ganache:
To make the ganache, add chocolate, butter, salt, and vanilla into a bowl. Set asideIn a small pan over medium heat, heat cream and sugar until hot but just before boiling
Pour the heated cream and sugar over the bowl of chocolate and let it set for 1 minute. Stir until smooth
Set in the fridge until cooled but not hard
Once it is cooled, whip with a hand mixer or in a stand mixer for 1-2 minutes until fluffy and light
Ice the cake with the whipped ganache
Notes
The cake batter recipe is based on Hershey's famous black magic cake