Cranberry port source

This should be made well ahead of time. After tremendous success of my first attempt, after Christams I went and bought as much cranberries as I could get at local Waitrose at half-price and made enough to have a few bottles for the next couple of years. I am told that the sauce tasted even better matured for a year or two.

Ingredients:

300g fresh cranberries
100ml port
1 small stick cinnamon, snapped in half
1 orange finally zested and juiced
140g caster sugar (or to taste) – I always put less sugar than recipes call for and all the alcohol in this preserves it sufficiently
1 tbsp Grand Marnier or Cointreau (which is what I used)

Place the cranberries, port, cinnamon, orange juice and zest in a small non-corrosive saucepan. Bring to the boil and simmer uncovered until the berries begin to pop and soften. Stir in the sugar and Cointreau, then adjust the sweetness to taste. The sugar will toughen the cranberries, so do not add it until this stage.
Remove the cinnamon stick and allow the sauce to cool before serving. It will thicken as it cools.