Preheat your oven to 350°F (175°C). Grease and flour three cake pans in sizes 8-inch, 10-inch, and 12-inch.

In a large bowl, mix flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add eggs, milk, oil, and vanilla extract. Mix well for 2 minutes. Carefully stir in boiling water until smooth.

Pour equal amounts of batter into each prepared pan and bake for 30-35 minutes or until a toothpick comes out clean. Cool in pans for 10 minutes before transferring to a wire rack.

In a large bowl, beat softened butter until creamy. Gradually add powdered sugar, mixing well. Pour in heavy cream and vanilla, and beat until fluffy.

Divide frosting into two bowls and tint one red and the other blue using food coloring.

Once cakes are cool, level the tops with a knife if necessary. Place the largest layer on a cake stand and spread blue frosting on top.

Add the middle layer with red frosting, and top with the smallest layer. Frost the whole cake with red frosting.

Use remaining blue frosting for web designs, and decorate with Spiderman figurines and edible glitter if desired.