Preheat your oven to 350°F (175°C). Grease your cake pans thoroughly with butter or cooking spray and line the bottoms with parchment paper.

Dust the greased pans lightly with cocoa powder.

Sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt in a large bowl.

In a separate bowl, whisk together the eggs, buttermilk, hot coffee, oil, and vanilla until fully combined.

Pour the wet ingredients into the dry mixture and mix on low speed for 30 seconds, then scrape down the bowl and increase speed to medium for 2 minutes.

Divide the batter evenly between the prepared pans and bake for 30-35 minutes, testing with a toothpick.

Let the cakes cool in the pans for 10 minutes before inverting onto cooling racks.

Beat softened butter until light and fluffy, then gradually add sifted powdered sugar and cocoa powder.

Add heavy cream, vanilla, and salt, and beat until smooth and fluffy.

Level any domed tops of the cakes, place the first layer on a serving plate, and spread frosting between layers.

Apply a thin crumb coat of frosting over the entire cake, refrigerate for 15-20 minutes, then apply the final coat of frosting.