COMBINE: Add all of the ingredients to a saucepan over medium heat. Cook, stirring occasionally, until the cranberries start to break down and the sauce starts to thicken and come together, about 5 minutes.
SMASH: Use a potato masher to gently press down on the warm cranberry mixture so that some of the cranberries are lightly crushed. (I like to leave quite a few whole cranberries, but you can mash them as mush or as little as you like!). Continue warming the cranberry sauce, stirring often, until it thickens and you can pull a spatula through the mixture cleanly, about 10 minutes. Remove from the heat.
SERVE: Remove and discard the rosemary sprig. The cranberry sauce can be served warm or room temperature, as you like. It will keep nicely in the fridge, in an airtight container, for a week or so and is even better once it’s been set aside at least overnight so that the flavors can mingle together. The cranberry sauce can be frozen for up to 3 months in an airtight container.
Any orange will do, but blood oranges are so seasonal and lovely I couldn’t resist them. Sub in whatever oranges you have to hand and add at least a good generous teaspoon of orange zest.