pour double cream into a sterilised jar, screw lid on tight and shake, shake, shake 'till your arm feels like it's going to drop off
suddenly, the cream will become solid...the curds have separated from the whey
pour away the whey and wash the curds
you then need to pat the curds between wooden spoons to make sure you get all the whey off
and you are left with butter!
add a little salt and chill to firm up a wee bit