Preheat your oven to 350 degrees F. It’s essential to start with a preheated oven to ensure even baking. Grease three 8-inch x 2-inch round cake pans generously with nonstick cooking spray. Don’t forget to line the pans with parchment paper; then, spray them again to make sure your cake comes out smoothly.
In the bowl of a stand mixer, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, salt, and espresso powder, if using. This combination creates a dry mix that will provide structure to your cake.
In a medium bowl, whisk together the buttermilk, oil, and vanilla extract. This wet mixture is crucial for adding moisture and flavor to the cake.
With the stand mixer on low speed, slowly add the buttermilk mixture. Add the eggs, one at a time, and mix until well combined. This step is where the batter starts to come together.
Gradually add the hot water to the mixture, stirring just to combine. Stop to scrape down the sides of the bowl to ensure everything is well incorporated. The batter will be thin, which is perfectly okay; it’s part of what makes the cake so moist.
Divide the batter evenly among the prepared pans. Bake for 22 to 28 minutes, or until a toothpick comes out clean when inserted into the center of the cakes. Keep an eye on them to prevent overbaking!
Remove the cakes from the oven and set them on a wire cooling rack. It’s important to let them cool in the pans for 30 minutes before turning them out onto a cooling rack to cool completely. You can wrap the cake layers in plastic wrap and chill in the refrigerator or freezer for easier handling later.
To make the frosting, using a stand mixer fitted with the paddle attachment, beat the butter until creamy and lighter in color, about 3 minutes. Make sure to scrape down the bowl halfway through.
With the mixer on low, gradually add the confectioner’s sugar, 2 cups at a time. Start with 6 cups and adjust according to your desired sweetness. Add the cocoa powder for that luscious chocolate flavor.
Pour in 6 tablespoons of heavy cream, vanilla extract, and salt. With the mixer on low, add the melted chocolate and mix for an additional 2 to 3 minutes, until the frosting is light and fluffy. If it’s too thin, gradually add more sugar; if too thick, add more heavy cream, a teaspoon at a time, until you reach the desired consistency.
To assemble the cake, ensure your cake layers are flat. If they have a rounded dome, carefully level the tops with a sharp serrated knife. Place the first layer bottom side up on a flat plate or cake stand.
Using a knife or offset spatula, spread the top of the first layer evenly with buttercream. Place the second layer on top, top side up, and spread more buttercream evenly over the top. Repeat with the third layer, frosting the top and sides of the cake for a beautiful finish.
Decorate with sprinkles, chocolate shavings, or chocolate chips, if desired. Each addition adds a personal touch to your beautiful creation!
Finally, use a sharp knife to cut the cake into pieces and serve. Enjoy the delicious results of your hard work!