Mix together 280g butter and 150g light brown sugar. Sift and gradually add 420g icing sugar and then add 140g plain flour, 0.75tsp salt, 3tbsp milk and 2.5tsp vanilla. Nom!
This makes 24 by the way, so half it for a standard batch of 12. It took me long enough to figure this version out so I'm sticking to making 24 cakes. You can never have too many cupcakes!