Prepare a boiling water bath canner and enough jars to hold 7 half pints of product.

Combine the berries and sugar in a large, non-reactive pot. Stir to combine. Let sit for 30 minutes or so, until the berries are mostly defrosted.

Place the pot on the stove over high heat and bring to a boil. Reduce the heat to medium-high and cook, stirring regularly, until the jam thickens. This should take between 20 and 25 minutes. Because of the presence of the cranberries, this jam will pass the sheet test on a spatula.

When the jam is finished, remove the pot from the heat.

Funnel the jam into the prepared jars, leaving 1/2 inch headspace.

Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 10 minutes.

When the time is up, remove the jars and set them on a folded kitchen towel to cool. When the jars have cooled enough that you can comfortable handle them, check the seals. Sealed jars can be stored at room temperature for up to a year. Any unsealed jars should be refrigerated and used promptly.