Ingredients for 2 cups jam:
2 pints fresh blueberries (1 1/4 pounds)
1/2 cup sugar, divided
1/4 cup cool water
1 cinnamon stick
Combine blueberries, 1/2 cup sugar, water and cinnamon stick in a non-reactive* saucepan. Cover the pan, bring to a simmer, uncover and simmer for 10 minutes.
Strain the jam through a sieve, return the liquid to the pan and simmer for 1 -2 minutes on medium high. Reduced juices will coat a metal spoon.
Return the berries to the pan. Stir them into the juices and let the jame stand for 15 minutes. Return the mixture to a boil and stir until the jam is so thick the bottom of the pan is exposed when you pull a spatula across it.
Off the heat, remove the cinnamon stick and pour the hot jam into sterilized jars** to within 1/2 inch of the rim. Wipe the lip iclean of any drips. Attach a new lid and screw on the cap. Invert the jar for 15 seconds. Turn upright and allow the jars to cool on a rack. Store in a cool place in the kitchen away from direct light.
* Avoid uncoated aluminum pans and stainless steel that does not have a heavy alloy base to improve conduction.
** Submerge jars in a pot fitted with a rack so the jars don't rest on the bottom. A pasta pot with a slotted insert is perfect for this job.