Adam bought some cream to make caramel that he never got around to making. There are 3 quarts but there was only one that needed to be used up now...the other 2 have use by dates a little further out. But I needed to use it or lose it...and since we were nearly out of butter I went to work on it.
You can only fill the container 1/3 full since it expands as it becomes butter. I use a quart canning jar so that meant three different batches to finish off the quart. I just shake, shake shake until it finally turns into butter. I tried a few different techniques and what seemed to work best was to just shake up and down for about 20-30 minutes until it gets to the point where it becomes so stiff it doesn't feel like it's moving anymore. Then, you take an end in each hand and shake side to side kind of forcefully. In a minute or two, the buttermilk suddenly separates from the butter.
Here's different stages of the cream. The square tupperware had whipped cream in it. The jar had the stuff that was so stiff, it felt like it wasn't moving, just minutes away from being butter.
Once you have butter, drain the milk into one container and the butter will go on a board (though I show it in another container because I was working batch by batch collecting it all before I worked out the buttermilk).
Put the butter on a board and work the butter with a paddle (had to use a wooden spoon) pressing as much buttermilk out as possible. I collect this milk too. Then, you put it under the faucet and work it some more with the water flowing over it. It's important to work as much of the buttermilk out as possible to keep it from going rancid sooner.
Once you are satisfied that the buttermilk is out, sprinkle some butter on it to help preserve it. Work the butter in, then you're done.