• Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans and line the bottoms with parchment paper.
• In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.
• In a separate bowl, whisk together buttermilk, oil, eggs, and vanilla extract.
• Add the wet ingredients to the dry ingredients and mix until just combined. Don't overmix.
• Slowly stir in hot coffee until the batter is smooth.
• Divide the batter evenly between the prepared cake pans.
• Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
• Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.

To make the chocolate ganache frosting:

• Place chopped chocolate in a heatproof bowl.
• Heat the heavy cream in a saucepan over medium heat until it just begins to simmer.
• Pour the hot cream over the chocolate and let it sit for 5 minutes without stirring.
• Gently whisk together the chocolate and cream until smooth and glossy.
• Let the ganache cool slightly before frosting the cake.

To assemble the cake:

• Place one cake layer on a serving plate or cake stand.
• Spread a layer of chocolate ganache frosting over the top.
• Place the second cake layer on top and frost the entire cake with the remaining ganache.