These are such a treat – they taste just beautiful and look pretty smart too!
Preheat oven to 180⁰C and line a muffin tin with paper cases.
Whisk the egg whites until soft peaks form then set aside.
In another mixing bowl, cream the butter and sugar until pale and fluffy, add the oil, yolks and vanilla and beat for a couple of minutes.
Sift together the flour, corn or rice flour and cocoa powder with a pinch of salt.
Add this to the butter/sugar mixture, alternating with the buttermilk until all combined.
Now fold in the vinegar and food colouring.
Fold in the egg whites very gently until just combined.
Divide mixture among the cupcake cases and place in the oven to bake for 20 minutes or until firm to the touch.
Let cupcakes cool on a wire rack while you make the frosting.
For the frosting, combine all ingredients in the bowl of an electric mixer and beat until smooth.
Transfer frosting into a snap-lock plastic bag and snip one of the ends off, pipe mixture on top of the cooled cupcakes and smooth the tops with a little spoon.