Put all the ingredients except the milk into a food processor and blitz till smooth. Pulse while adding the milk slowly to make a soft, dropping consistency. (If you don’t have a processor, soften the butter then cream the butter and sugar, add the dry ingredients and then the milk and mix well.)
Divide the mixture between 12 paper cases in a muffin tray. It doesn't look like much in each paper case - but fear not - it will rise!
Bake for 15-20 minutes or until the cakes are golden on top. Col on a rack.
ice when cool. To make the icing; first grate the rind from the orange and set aside, then juice the orange.
Melt butter, add sifted icing sugar, orange juice. Mix well.
Ice each cupcake, then put rind on top - just to give it that little fancy edge.
For a difference, use whole lemon instead of orange.