How to Make It
Combine blueberries and sugar in a flat-bottomed kettle; cook over low heat, stirring until sugar dissolves. Bring to a rolling boil, stirring constantly, until mixture registers 220° on a candy thermometer or until mixture sheets from a cold metal spoon. Remove from heat; skim off foam.
Quickly ladle jam into hot sterilized jars, leaving 1/4-inch headspace. Cover at once with metal lids, and screw bands tight. Process jam in boiling water bath 10 minutes.
Note: Blackberries may be substituted for blueberries. If seedless jam is preferred, crushed blackberries may be heated until soft and pressed through a sieve or food mill; add sugar, and proceed as directed.
Oxmoor House Homestyle Recipes