Preheat oven to 350°F. Grease 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 another bowl, mix buttermilk, oil, eggs, and vanilla extract.

Gradually add the wet ingredients to the dry ingredients, stirring just until combined.

Slowly pour in the hot coffee while mixing. The batter will be thin—this is normal.

Divide batter evenly between the prepared pans.

Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

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

Beat butter until smooth and creamy.

Gradually add powdered sugar and cocoa powder, mixing on low speed.

Add salt, vanilla, and heavy cream, then beat until light and fluffy. Adjust consistency with more cream or powdered sugar if needed.

Place one cake layer on a plate and spread a generous amount of frosting on top.

Add the second cake layer and frost the top and sides evenly.

Decorate as desired and let the cake set for a few minutes before slicing.