Using the food processor, mix the butter, icing sugar, orange zest and vanilla extract until light and fluffy.  Tip into a large bowl and add the sifted flours, cranberries and rub mixture as if making shortcrust pastry until the mixture resembles bread crumbs.

Spoon over the milk and bring the breadcrumb mixture together into a ball.

Divide into 2-3 balls to make the mixture easier to manage. Knead the balls of dough on a floured surface until smooth then roll into logs around 6-7cm in diameter.  Wrap each log with parchment paper and place in a freezer bag in the fridge for about 1 hour until firm or freeze until needed (up to 1 month).

Meanwhile pre-heat the oven to 160c and line a couple of baking trays with parchment paper.

When the logs have firmed up, unwrap them and using a sharp knife cut into slices 1cm thick.  Place about 3cm apart on the baking trays and bake for around 18-20 minutes until just golden.  Cool on wire racks.