Chocolate cupcakes recipe

Ingredients

• 70 g butter, softened
• 125 g caster (superfine) sugar
• 1 large egg
• 25 g self-raising flour
• 85 g plain (all-purpose) flour
• 0.5 tsp bicarbonate of soda (baking soda)
• 40 g cocoa powder
• 80 ml milk
• 1.5 tsp malt vinegar (alegar)