Preheat your oven to 350°F (175°C). Grease and line two 8-inch round cake pans.

In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, salt, and sugar until well mixed.

Add in the eggs, buttermilk, vegetable oil, and vanilla extract. Mix until smooth.

Slowly pour in the hot coffee; the batter will be thin.

Divide the batter evenly between the pans and bake for 30–35 minutes, or until a toothpick inserted comes out clean.

Let the cakes cool completely.

To prepare the fudge filling, heat the heavy cream until hot (but not boiling). Pour it over the chocolate chips and butter, and let it sit for 2 minutes.

Stir until the mixture is smooth. Chill in the fridge for 15–20 minutes until thickened.

Place one cake layer on a plate. Spread the fudge filling over it, place the second layer on top, and chill for 15 minutes.

For the ganache, heat the cream and pour it over the chocolate chips. Let it sit for 2 minutes.

Whisk until silky. Stir in the butter for extra shine if desired.

Pour the ganache over the chilled cake, allowing it to drip down the sides.

Optionally top with chocolate curls or a sprinkle of sea salt.