Preheat your oven to 350°F (175°C) and grease two 8-inch round cake pans with unsalted butter, lining the bottoms with parchment paper.

In a large bowl, sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Mix on low until combined.

In another bowl, whisk together the buttermilk, vegetable oil, eggs, and vanilla until smooth. Pour into the dry ingredients and mix on low.

Slowly pour in the hot coffee while mixing on low, until the batter is thin and well combined.

Divide the batter evenly between the prepared pans and bake for 35-40 minutes, checking with a toothpick.

Once baked, cool the cakes in the pans for about 30 minutes, then turn them out onto a wire rack to cool completely.

To make the frosting, melt the chocolate over a double boiler and let it cool slightly. Beat the butter until fluffy, then mix in the egg yolk and vanilla.

Gradually add the confectioners’ sugar, mixing until smooth, then incorporate the melted chocolate until combined.

Frost the cooled cake layers with frosting, stacking them with frosting in between and covering the top and sides.

Slice and serve your moist chocolate cake, enjoying it at celebrations or as a special treat!