Measure your dry components carefully before starting the mixing process. Combine the all-purpose flour, granulated sugar, unsweetened cocoa powder, baking soda, and fine sea salt in your mixing vessel. (I tried using Dutch-process cocoa the first time, the cake didn't rise properly because it lacks the acid needed to react with the baking soda. Stick to standard natural cocoa powder here.) Whisk the mixture continuously with a balloon whisk using a circular motion for exactly 45 seconds at room temperature. You'll see the pale white flour and dark brown cocoa blend into a uniform, light tan powder with no visible streaks. This thorough blending ensures the leavening agent distributes evenly so your cake rises uniformly without large holes.

Crack the large eggs directly into the center of the dry mixture, then pour in the buttermilk, vegetable oil, and pure vanilla extract. Use a heavy wooden spoon to stir the liquid into the powder using a wide, sweeping motion from the edges inward. Work the ingredients together at room temperature for about 1 to 2 minutes until the flour disappears completely. The mixture will transform into a very thick, matte, dark brown paste that resists your spoon slightly. Do not worry about a few small lumps at this stage because the hot liquid in the next step will smooth them out nicely. Miss this window of full incorporation and you'll end up with pockets of dry flour baking into the core of your cake crumb.

Pour the hot brewed coffee slowly into the thick batter paste while whisking gently with your free hand. Use a steady, J-shaped folding motion with a flexible rubber spatula to draw the liquid from the bottom up to the top. Continue this gentle agitation for 60 seconds until the liquid incorporates fully into a sleek, pourable consistency. You'll smell a sudden burst of roasted chocolate aroma as the heat blooms the cocoa solids, and the batter will turn into a thin, glossy, dark mahogany liquid with tiny bubbles popping on the surface. If you skimp on the hot liquid, the cocoa crystals won't dissolve properly. Whisk gently so you don't overwork the gluten inside the flour.

Divide the liquid batter evenly into three greased 9-inch round cake pans, filling each pan about halfway up the sides. Place the pans carefully onto the middle rack of your 350°F preheated oven. Bake steadily for 28 to 32 minutes without opening the oven door during the first 20 minutes to prevent a temperature drop. The liquid batter will set into a firm, dull, deep espresso-colored sponge that springs back lightly when touched in the center. You'll see the edges pull away slightly from the pan walls, and a wooden toothpick inserted into the middle will come out clean. Pull the cakes out too early and the centers will collapse into dense, gummy puddles as they cool down.

Place the first cooled cake layer onto your serving plate, then scoop a generous cup of chocolate fudge frosting onto the center. Spread the frosting unevenly to the edges using an offset spatula, then stack the second layer on top and repeat. Finish by coating the third layer and the outer sides with the remaining frosting. The assembled cake will present a rustic, multi-tiered silhouette with dark brown frosting sealing the horizontal seams. You'll see a thick, rich, spreadable texture that catches the light with a slight sheen across its non-uniform surfaces. (My first batch slid apart because I tried frosting the layers while they were still slightly warm. Wait until they are completely cool to the touch.)