Preheat your oven to 350°F (175°C) and prepare two 8-inch round cake pans by greasing and flouring them.

In a large mixing bowl, sift together the dry ingredients: flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk well.

In another bowl, whisk together the wet ingredients: eggs, vegetable oil, buttermilk, and hot coffee until well combined.

Gently fold the wet ingredients into the dry mixture using a spatula until just combined without overmixing.

Divide the batter evenly between the two prepared pans and bake for 25 to 30 minutes until a toothpick comes out clean.

Allow the cakes to cool in the pans for 10 minutes before turning them out onto a wire rack to cool completely.

Melt the semisweet chocolate until smooth, then allow to cool slightly. Whip the heavy cream with powdered sugar and vanilla until stiff peaks form.

Fold the melted chocolate into the whipped cream carefully to keep the airy texture.

Place one layer of cake on a platter, spread half of the mousse on top, and add the second layer followed by the remaining mousse.

Refrigerate the cake for at least 3 hours or overnight for the best results.

Prepare the ganache by heating the cream, then stirring in chocolate until melted, followed by corn syrup and butter.

Pour the ganache over the cooled cake and let it set before slicing and serving.