Instructions

1. Preheat oven to 180 C (350 F) standard / 160 C (320 F) fan-forced. Line a 12 hole muffin tin with cupcake liners.
2. In a large mixing bowl, sift flour, baking soda and cocoa powder, then add the sugar – give it a good whisk. Pop the butter into the microwave for a short time, 20 seconds or so at a time, stirring until it is just melted. Give it a stir with a fork to eliminate any lumps.
3. In a separate mixing bowl, add eggs, vanilla and butter and whisk together until smooth. Add yogurt and give it a stir – don’t worry if it goes a little lumpy. In a separate small bowl, add the food colouring and vinegar.
4. Add the wet mixture into the dry mixture, along with the food colouring and gently fold until just combined. Spoon the mixture into the prepared liners and pop into the oven.
5. Bake for approximately 18 minutes or until a skewer inserted comes out clean. Set cakes out onto a wire rack and leave to cool completely.
6. To make the frosting, place butter in a large mixing bowl and beat with an electric mixer on medium speed for a couple of minutes until pale and creamy. Meanwhile melt the chocolate in a microwave, stirring in between 20 second bursts, until just melted and set aside to cool a little.
7. Once the butter is very pale and creamy, add half of the powdered sugar and one tablespoon of milk and beat on low until the sugar is incorporated. Then, add the rest of the sugar and the milk, and again beat on slow until the sugar is incorporated before turning up to medium for another minute or so.
8. Next, add in your melted chocolate to the buttercream mixture, ensuring the chocolate is still smooth and melted but is not warm. Beat until the chocolate is completely mixed through. Transfer your frosting to a piping bag fitted with a large circular tip. Pipe swirls onto each cupcake.