Preheat your oven to 180°C.
Prepare your muffin tin, by lining each hollow with a paper case.
In a bowl sift together the dry ingredients (flour, castor sugar, salt, cocoa and bicarb) and set aside.
In another, larger, bowl mix all the wet ingredients (oil, buttermilk, eggs, food colouring, vinegar and vanilla).
Add the wet ingredients to the dry ingredients, and combine.
Spoon into your cupcake cases, filling each to 3/4 full. Bake for 18-20 minutes or until cooked through. Remove from the oven and set aside to cool.
In the meantime, prepare your icing by beating the butter and cream cheese together with a wooden spoon until well combined (about 3 minutes).
Gradually add the icing sugar, beating all the while until it forms a smooth icing. Adjust the consistency by adding a little more icing sugar if required. Then add the lemon juice and/or the vanilla to taste.
Recipe reprinted with permission of Julie Donald.