Confession here: I like seeds in my berry jam. I don’t know why, either some trauma forced on me by my older brother, or perhaps faded memories of my mother making jams or even some totally unrelated reason. The point is my berry jam must have seeds. Do you have any idea how difficult it is to find blackberry jam with seeds? Raspberry? No problem, but find a jar of blackberry without that insidious word “seedless” on the label? Good luck. Either you spend an inordinate amount of time searching your supermarket, or go to a farm or specialty market and shell out twice the cash. I look for BOGO’s on berries. It’s like getting jam free, almost.
Or….
Google (the worlds 42) “small batch jam” and find 461,000 results in 0.44 seconds.
I read a lot of them and boiled it down (bad pun) to this:

• Measure equal weights (not volumes) washed berries and granulated sugar. Obviously for sweeter jam add more sugar, tarter, less. Duh.
• Mash berries in a saucepan, heat then add sugar in small aliquots. Use a large enough saucepan or you will end up washing two of them. Been there, done that, no t-shirt.
• Cook at a moderate boil until the temperature reaches 220 deg. and it begins to thicken. Cook less for thinner (think dessert topping) or more for thicker.
• Skim the light colored foam off the top as it boils.
• While it is cooking put a canning jar (about a pint size for a pint of berries, go figure) filled to about an inch from of the top with water into the microwave and cook until boiling vigorously.
• Pour the boiling water out into a small bowl containing your canning lid and funnel.
• Wait a minute. You aren’t really sterilizing because you will just keep this in the fridge for quick use.
• Pour the still very hot jam into the jar using the funnel, put on the lids, screw on the top and you are done, except for the clean up. One pan, one spoon and a funnel.
• Total time, less than 30 min.