1. Preheat and Prepare Pans:

Preheat oven to 350°F (180°C).

Grease two 8-inch round baking pans. Line the bottoms with parchment paper rounds, then lightly grease the parchment paper. Dust the pans lightly with flour or cocoa powder, tapping out any excess. Set aside.

2. Combine Dry Ingredients:

In a large mixer bowl (or just a large bowl), add the granulated sugar, flour, cocoa powder, baking powder, baking soda, and salt. Whisk or stir with the mixer on low speed just to combine everything evenly.

3. Combine Wet Ingredients (Except Hot Liquid):

In a separate medium-sized bowl, whisk together the room temperature eggs, buttermilk, oil, and vanilla extract until well combined.

4. Combine Wet and Dry:

Add the wet ingredients to the dry ingredients in the large bowl.

Beat on medium speed with an electric mixer (or whisk vigorously by hand) until well combined, scraping down the sides of the bowl as needed (about 2 minutes with a mixer).

5. Add Hot Liquid (Key Step!):

Reduce mixer speed to low (or prepare to stir carefully by hand).

Slowly pour the hot water (or hot coffee) into the batter. Mix on low speed (or stir gently) just until well combined. The batter will be very thin – this is correct!

6. Bake the Cake Layers:

Pour the thin batter evenly between the two prepared cake pans.

Bake for 30 to 35 minutes, or until a wooden toothpick inserted into the center of the cakes comes out clean or with a few moist crumbs attached. Do not overbake, as this can negate the moistness.

7. Cool the Cakes:

Let the cakes cool in the pans on wire racks for about 10 minutes.

Then, carefully invert the cakes onto the cooling racks, remove the parchment paper, and let them cool completely before frosting.

8. Make the Chocolate Frosting:

Combine the melted butter and cocoa powder in a medium bowl. Whisk until smooth.

Alternately add the sifted powdered sugar and the milk, beating (with mixer or by hand) after each addition until smooth. Start and end with powdered sugar if beating by hand.

Stir in the vanilla extract (and pinch of salt if using unsalted butter).

Beat or mix for several minutes until the frosting is smooth, glossy, and reaches a good spreading consistency. It will be denser and fudgier than a standard buttercream.

9. Assemble the Cake:

Place one cooled cake layer on a serving tray or cake stand.

Spread a generous amount of the chocolate frosting evenly over the top.

Place the second cake layer on top.

Frost the top and sides of the cake smoothly with the remaining frosting.

10. Serve:

Slice and serve! This cake is delicious at room temperature.