I picked 4kg of blackberries the other day from the Walthamstow marshes in London (so much more than back in the country!) and made two batches of jam with 2kg (with and without apples, and froze the rest) this was the best. It has a bit of a Christmasy taste because of the cinnamon and nutmeg. Here's my recipe - finite measurements are for squares :-)
Learn how to sterilise jars two ways with our handy step-by-step guide and video.