Wacky web halloween cake

Name: Wacky web halloween cake
Prep time: 45 min
Cook time: 30 min
Total time: 1 h 15 min
Cuisine: Australian
Ingredients: 125 gram butter, softened; 1 teaspoon vanilla extract; 1 1/2 cup (330g) caster sugar; 2 eggs; 1 1/2 cup (225g) plain flour; 2 tablespoon cornflour; 2 tablespoon cocoa powder, sifted; 1 cup (250ml) buttermilk (see tips); 1 tablespoon red food colouring; 1 teaspoon white vinegar; 1 teaspoon bicarbonate of soda; 4 black toy spiders; smarties; 500 gram cream cheese, softened; 250 gram butter, softened; 2 teaspoon vanilla extract; 5 cup (180g) soft icing sugar; black food colouring