Preheat oven to 350°F (175°C). Grease and line your cake pan with parchment paper.
In a large bowl, whisk together flour, sugar, baking powder, and salt.Add eggs, milk, melted butter, and vanilla extract. Mix until smooth and lump-free.
Pour batter into prepared pan. Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean.
Remove cake from oven and let it cool in the pan for 10 minutes. Transfer to a cooling rack and cool completely before decorating.
Beat butter until creamy. Gradually add powdered sugar, milk, and vanilla extract. Beat until light and fluffy.
Divide frosting into bowls:Tint one bowl redTint one bowl blueTint a small portion black for web details Spread red frosting evenly over the cake.Pipe black lines in a spider-web pattern.Add blue frosting accents or borders as desired.