Tip the sugar and orange juice into a pan over a medium heat and bring to the boil. Add the rosemary sprig and stir in the cranberries. Simmer for 10 mins until the berries are tender but still holding their shape, and the sauce is sticky.

Remove from the heat and discard the rosemary sprig, then leave to cool and thicken slightly before serving. Once cool, will keep covered and chilled for a week or frozen for a month. Defrost thoroughly before serving.