Butter is very easy to make yourself and is a fun project for any kids needing something to do in the kitchen.
1. Take the cream out of the fridge and let it warm to room temp for about half an hour.
2. Pour enough cream into the mason jar to come a third of the way up the sides. You need to leave plenty of air space so that the cream can really move around.
3. Screw the lid tightly. Now shake the jar up and down and all around so that the cream bounces against the lid. It's important not to stop shaking until the butter forms.
4. First you'll feel the cream slop around in the jar, then you'll notice that it stops slopping and goes silent. At this stage you just have whipped cream. Keep shaking - it may take 10 minutes or half an hour.
5. All of a sudden the sound and the sensation will change. You'll have a big lump sloshing around in a thin, watery liquid. The lump is your butter and the liquid is buttermilk - carefully open the lid and take a look inside.
6. Now you have to wash your butter under the cold tap: drain the buttermilk off into a mug and fill the jar with cold water. Swirl the lump of butter around in the water and pour the water carefully away. Do this again and agin until the water is clear.
7. Put the butter lump on the board a press down on it with the back os a wooden spoon or use your hands to force out any buttermilk still inside. This is important, because any buttermilk left inside will make it go sour.
8. You can now wrap and refrigerate your homemade butter - or eat it straight away.
From The River Cottage Family Cookbook