I tried this recipe, on a much smaller scale, when I had a bit of heavy cream that had been hanging around in my fridge for a while. I figured it was use it or lose it time, so why not give it a go? The kids and I enjoyed the shaking (and shaking and shaking and shaking), and the butter was actually quite good. We sampled it the night we made it, then I used the rest in a batch of biscuites or scones or something.
organic cream (not ultra-pasteurized) (I used non-organic, and I have no idea about the pasteurization level!)
quart or half gallon mason jars (I used a rubbermaid container, since I had just a tiny bit of cream.)
1. Leave the cream at room temperature for a few hours until it's fully warmed to room temperature.
2. Pour room temperature cream into jar. Important: The jar should be double the size of the amount of cream you are using. If you are shaking a pint of cream, you need a quart jar.
3. Make sure the cap the screwed on very tight (or the plastic lid is snapped tightly). Shake it really really really well. Take turns with each of the kids. You'll feel the progress soon.
4. Keep right on shaking until no more butter will form. (There will be a thin white liquid as well.)
5. Separate the liquid from the butter.
6. Place butter in a bowl and run very cold water over it. Press and squeeze to get as much of the buttermilk out as you can. Keep going until the water is clear.
7. You can add salt if you want.
8. Pack in refrigerator or freezer proof containers. I just kept the same rubbermaid I had used to make the butter.
9. You should be able to keep the butter, if frozen, for up to a year.