How to make butter

Pour the double cream into a cold, sterilised mixing bowl. If it's homogenised, it will still whip, but not as well. If you're using raw cream and want a more traditional taste, leave it to ripen in a cool place, where the temperature is about 8°C (46°F), for up to 48 hours. Whisk the cream at a medium speed in a food mixer until it is thick. First it will be softly whipped, then stiffly whipped. Continue until the whipped cream collapses and separates into butterfat globules. The buttermilk will separate from the butter and slosh around the bowl.
Photograph: Peter Cassidy

Turn the mixture into a cold, spotlessly clean sieve and drain well. The butter remains in the sieve while the buttermilk drains into the bowl. The buttermilk can be used to make soda bread or as a thirst-quenching drink (it will not taste sour). Put the butter back into a clean bowl and beat with the whisk for a further 30 seconds to 1 minute to expel more buttermilk. Remove and sieve as before. Photograph: Peter Cassidy

Fill the bowl containing the butter with very cold water. Use the butter bats or your clean hands to knead the butter to force out as much buttermilk as possible. This is important, as any buttermilk left in the butter will sour and the butter will go off quickly. If you handle the butter too much with warm hands, it will liquefy
Photograph: Peter Cassidy

Drain the water, cover and wash twice more, until the water is totally clear
Photograph: Peter Cassidy

Weigh the butter into 110g (4oz), 225g (8oz) or 450g (1lb) slabs. Pat into shape with the wet butter hands or bats. Make sure the butter hands or bats have been soaked in ice-cold water for at least 30 minutes before using to stop the butter sticking to the ridges. Wrap in greaseproof or waxed paper and keep chilled in a fridge. The butter also freezes well
Photograph: Peter Cassidy