Preheat your oven to 350°F (175°C) and gather your ingredients. Combine the cake mix, eggs, water, and vegetable oil in a large mixing bowl. Mix on medium speed for about 2 minutes until smooth.

Pour the batter into two greased round cake pans. Bake for 25-30 minutes or until a toothpick comes out clean. Let the cakes cool in the pans for 10 minutes.

While cooling, make the frosting by beating together softened butter, powdered sugar, cocoa powder, and heavy cream until creamy and fluffy, about 3-4 minutes.

Once cooled, place one cake layer on a serving plate, spread frosting on top, and place the second layer on top. Use the remaining frosting to cover the cake.

Melt the white chocolate in 30-second intervals until smooth. Transfer to a piping bag and drizzle on top in circular patterns. Swirl with a toothpick to create the spiderweb effect.

Add candy eyes and black sprinkles for decoration. Allow the design to set before slicing and serving.