Next, take your jar and shake, shake, shake... you will need to shake anywhere from 10 to 30 minutes and then the fat molecules will begin separating and you'll start getting globs of yellow butter. Keep shaking!
Soon, it will look like most of the cream has turned into butter and then pour out the milk that is left. Add some cold water to the butter and shake again for a minute or two and pour out. Do this a few times and the water will be mostly clear that you pour out. You can then spoon out the butter from the container into a bowl and let it sit in the fridge for a while. Then, spoon the butter (mash it), trying to push out any water that may still be in the butter. Pour out or remove any water and you have your butter! This is a fun project and much healthier than buying the store bought. Have fun!