Preheat your oven to 180 degrees (fan forced) and line a muffin tray with 12 paper cases.
Melt the butter in the microwave and set aside to cool slightly.
Sift flour and cocoa into the bowl of an electric mixer, then add all the other ingredients.
Beat for approximately 3 minutes until ingredients have all combined and the mixture is smooth.
Divide the mixture amongst the cupcake cases and bake for 15 - 18 minutes or until a skewer inserted in the middle comes out clean.
Allow the cupcakes to cool in the tin for five minutes before transferring to a wire rack to cool completely.