Preheat oven to 350°F (175°C) and grease two 9-inch round cake pans. Combine all dry ingredients in a large bowl. In another bowl, whisk wet ingredients, then combine wet and dry until smooth.

Divide batter into pans and bake for 25-30 minutes. Cool in pans for 10 minutes, then transfer to wire racks to cool completely.

Melt white chocolate in intervals and do the same for dark chocolate. Set aside to ensure it remains runny.

Once cooled, place one layer on a platter, top with frosting, and place the second layer on top.

Using melted white chocolate, create spiderweb circles, then draw lines to form a web. Drizzle dark chocolate over the top.

Decorate with chocolate shavings and candy spiders as desired.