My mother-in-law, Trish, is the shortbread expert in our family, so I have stolen her recipe. She makes these delicious biscuits every year at Christmas and gives them to us all in beautifully wrapped jars.
Put the sugar in a food processor and process until finer.
Put the butter in the bowl of a freestanding electric mixer fitted with the paddle attachment. Add the vanilla seeds and cream the butter on low speed until very soft and pale, then increase the speed and add the sugar. Mix to combine well. Sieve the flour and cornflour together, then add to the creamed