Meanwhile, make the compote. Place the reserved cherry syrup in a small saucepan with the sugar and Cointreau or crème de cassis, if using. Bring to the boil over a high heat, stirring until the sugar dissolves, then lower the heat to simmer for about 10 minutes, until reduced by about half. Stir in the cranberries (which may cause the syrup to harden, but don’t worry) and continue to cook for a few minutes more, until the cranberries have softened. Remove and leave to cool completely.