Very good homemade butter

This is a really magical staple to make and one of those things you feel you are creating something out of nothing. You can make this in a jam jar by shaking it for a long time (about 20 minutes) until it thickens and finally separates, but it’s much quicker to use a stand mixer or even a food processor with a normal blade. Unsalted butter should be eaten within a couple of days but salting it means it can be kept for 2-3 weeks.