Preheat your oven to 350°F (175°C). Generously grease two 9-inch round cake pans and line the bottoms with parchment paper rounds to ensure easy release after baking.

In a large mixing bowl, combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt. Whisk thoroughly to eliminate any lumps and to evenly distribute the leavening agents and cocoa throughout the mixture.

In a separate medium bowl, lightly beat the eggs just until the yolks and whites are blended. Stir in the buttermilk, oil, and vanilla extract, mixing until well combined and smooth.

Pour the wet mixture into the dry ingredients and gently fold together using a silicone spatula or a hand mixer on low speed. The mixture will be thick and dense at this stage.

Gradually pour the hot coffee into the batter, stirring continuously until a smooth, thin batter forms. The batter will appear more liquid than traditional cake batters—this is expected and results in the cake's exceptionally moist texture.

Evenly divide the batter between the prepared pans. Bake for approximately 35 minutes, or until the center of each cake layer springs back lightly when pressed with a fingertip. A few moist crumbs clinging to a tester is normal for this richly textured cake.

Allow the cakes to cool in their pans on a wire rack for about 10 minutes. Then carefully turn them out onto the rack and peel off the parchment paper from the bottoms. Let the layers cool completely before assembling.

Once cooled, frost the cake with two batches of Easy Chocolate Buttercream. If not serving immediately, the unfrosted cake layers can be wrapped tightly and frozen for up to 3 months. A frosted cake, kept covered at room temperature, will stay fresh for about 3 days.