Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans.

In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt.

In a separate bowl, whisk together eggs, buttermilk, oil, and vanilla extract.

Add the wet ingredients to the dry ingredients and mix until just combined. Gradually stir in the hot water until the batter is smooth.

Pour the batter evenly into the prepared cake pans.

Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes, then invert them onto a wire rack to cool completely.

While the cakes are cooling, prepare the frosting. In a large bowl, beat the softened butter until creamy. Gradually add the powdered sugar, alternating with the milk, until smooth and fluffy. Stir in the vanilla extract.

Divide the frosting into two bowls. Leave one bowl white. Tint the other bowl with black gel food coloring until you achieve a dark black.

Once the cakes are completely cool, place one cake layer on a serving plate. Frost the top with a thin layer of white frosting.

Place the second cake layer on top. Frost the entire cake with a smooth layer of white frosting.

Transfer the black frosting to a piping bag fitted with a small round tip (or a ziplock bag with a corner snipped off).

Starting from the center of the cake, pipe concentric circles of black frosting, working your way outwards.

Using a toothpick or a thin skewer, drag lines from the center outwards through the black frosting to create the spider web effect. Wipe the toothpick clean between each drag.

Allow the frosting to set slightly before serving.