The Chilled Plate Test

1. Pour a bit of the fruit spread onto a plate and stick it in the freezer for a few minutes. When you take the plate out, check to see if any juice has separated from the pulp. (Alternatively, you can chill a plate in the freezer and then add a spoonful of preserves to see if it separates.) If separation occurs, the mixture needs to be cooked more. If it holds its shape, it's ready to be ladled into jars.

Special Thanks

1. The foregoing is excerpted from Tart and Sweet by Kelly Geary and Jessie Knadler. All rights reserved. Copyright © 2010 by Kelly Geary and Jessie Knadler.

1. Place blueberries, sugar, lemon zest and juice, and honey in a large saucepan and bring to a boil over medium-high heat. Reduce heat and simmer gently, 20 to 30 minutes, or until jam looks thick and glossy or until a food-grade thermometer registers 220°F, stirring often to prevent scorching. If you don't have a food thermometer, check for doneness using a chilled plate.
2. Ladle into hot jars, leaving ¼ inch headspace. Check for air bubbles, wipe the rims, and seal. Set jars in a pot of boiling water, ensuring that there is enough water to cover the lids by 1-inch. Let jars boil for 10 minutes. Processing at higher altitudes require additional time. Note that this jam may not set immediately but should do so after cooling. In some cases the set time may take several days according to reviews provided on this recipe.