Credit: Croi Duire
Peel, core, and coarsely chop the pears; wash and pick through the cranberries. Bring the water and sugar to a boil in a heavy bottomed saucepan. Add the spices (in a spice-bag, unless you like chewing on cinnamon stick fragments; I happen to be fond of candied ginger slices, so they are just tossed in to surprise the unwary).
Swish the spices around a bit, to let them start diffusing, then add the pears and berries. Bring back to a boil, then lower the heat and let everything simmer until all the berries have popped, the pears are tender, and the sauce is beginning to thicken, stirring occasionally.
Let cool, then refrigerate until fully set.