Black Velvet Halloween Cupcakes

Ingredients

• 200g plain flour
• 110g caster sugar
• 1&1/2 teaspoon cacao powder
• 3 large eggs
• 100g unsalted butter, at room temperature
• 150g buttermilk
• 1/2 teaspoon bicarbonate of soda
• 2 teaspoons baking powder
• 1 teaspoon white wine vinegar
• 1 teaspoon vanilla extract
• Black food colouring
• 120g unsalted butter, at room temperature
• 200g soft cream cheese
• 400g icing sugar
• 1&1/2 teaspoon vanilla extract
• Orange, green and purple food colouring
• Sprinkles