Preheat your oven to 350°F (175°C). Grease two 8-inch cake pans and dust with flour. In a large bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt.
In a separate bowl, beat the sugar, eggs, vanilla extract, and vegetable oil until the mixture is smooth and slightly fluffy. Gradually add the buttermilk, mixing well after each addition.
Slowly add the dry ingredients into the wet mixture, mixing on low until just combined. Carefully pour in the hot water, stirring gently to create a thin, smooth batter.
Divide the batter evenly between the prepared cake pans and tap lightly to remove air bubbles. Bake for about 35-40 minutes, until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
While the cakes cool, prepare the frosting by mixing powdered sugar and cocoa powder in a bowl. Add the softened butter, and beat with a hand mixer or whisk until crumbly.
Gradually add milk, one tablespoon at a time, and beat until the frosting is smooth, creamy, and spreadable. If it’s too thick, add a little more milk; if too soft, chill for a few minutes.
Level the cooled cakes with a knife or cake leveler if needed. Spread a generous layer of frosting on one cake layer, then top with the second layer. Cover the entire cake with a smooth layer of frosting using an offset spatula.
Fill a piping bag fitted with a small round tip with black gel food coloring diluted slightly with a little frosting to make it easier to pipe. Draw concentric circles on the cake’s surface to start the web pattern.
Using a small piping tip, draw straight lines from the center of the cake outward, forming a spider web pattern. Take your time to make the lines even and consistent.
Refine the web pattern by adding more lines or detailing as desired. Chill the cake for 30 minutes to set the frosting and web design before serving.
Slice with a sharp knife, revealing the moist chocolate layers and intricate web frosting. Serve and enjoy the spooky, delicious masterpiece!
