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

In a medium bowl, combine half of the Dutch-processed cocoa powder with 1 cup of hot brewed coffee. Whisk until smooth and let it cool.

In a large mixing bowl, sift together the all-purpose flour, remaining cocoa powder, granulated sugar, baking powder, baking soda, and fine sea salt.

In a separate bowl, whisk together the eggs, buttermilk, vegetable oil, and vanilla extract until fully blended.

Carefully pour the wet ingredients into the dry mixture. Stir gently until just combined.

Incorporate the cooled coffee-cocoa mixture into the batter, folding it in until smooth.

Divide the batter evenly between the two prepared cake pans and bake for 30-35 minutes.

Let the cakes cool in the pans for about 10 minutes, then transfer to wire racks to cool completely.

Melt together the semi-sweet chocolate, unsalted butter, heavy cream, and powdered sugar in a saucepan over low heat. Whisk until smooth.

Chill the frosting in the refrigerator for about 30 minutes until it thickens slightly.

Stack the first chocolate layer on a serving plate, spread frosting on top, then layer the second cake. Coat with remaining frosting.

Allow the cake to sit at room temperature for at least 15 minutes before serving.