1. Preheat the oven to 175 degrees Celsius. Line two baking trays with baking paper and set aside.

2. In a mixing bowl, sift and mix together dry ingredients - flour, cocoa, baking powder.

3. Using an electric mixer, cream together the butter and sugar until pale and fluffy. Beat in the eggs, one at a time. Add the vanilla and vinegar, mix well.

4. Add the food colouring and mix well. Use a spatula to make sure you scrape the bottom of the bowl.

5. Add the dry ingredient mix. Use a low speed on the mixer to mix until just combined and forming a soft and sticky dough.

6. Put the icing sugar mixture in a shallow bowl. Drop tablespoons of mixture into the bowl, rolling the mix to form a ball, then place on the baking sheet. Leave around 5cm between each ball - they will spread!

7. Bake for around 12 minutes, or until puffed up and cracked tops have formed. Cool on the baking trays for 2 minutes before transferring to a wire rack to cool completely.

8. Enjoy with a hot cup of tea or glass of milk.