For this method, you need to use your wire whisk attachment. I highly recommend using the splatter guard too as when the cream separates it can splatter a lot.
Once your wire whisk attachment is fitted, add the cream to the bowl. Then add fit the bowl guard.
Turn the stand mixer on, gradually increasing the speed from the lowest the highest. The cream should start to get thick as it starts to whip.
Keep the mixer going at its highest speed until the cream separates into butter and buttermilk. It can take anywhere from 2 to 5 minutes. Just be patient - it will happen!
Once the cream has separated and the butter has collected inside the wire whisk, turn the stand mixer off. Lay a muslin cloth over a clean bowl or jar and knock the butter out of the wire whisk and into the cloth. Use the cloth to squeeze out as much of the buttermilk as you can. Add this buttermilk to the buttermilk in the stand mixer bowl and set aside (you can use this for lots of different things).
Add the butter back to the stand mixer bowl and pour over one litre of icy cold water. Turn the stand mixer on and gradually increase from lowest speed to highest speed for around 30 seconds to one minute. Once the butter has collected in the wire whisk, turn the mixer off.
Lay the muslin cloth over a bowl again and knock the butter back into the cloth. Use a spoon or scoop to grab any stray bits of butter from the water before disposing of the water.
Use the muslin cloth to squeeze out as much of the water as you can from the butter. The more water you squeeze out the better.
Once you've strained the butter as much as you can, it's ready to use!
If you want to add salt to your butter, add the butter back to a clean stand mixer bowl and add up to 5g of salt. Turn the mixer on, gradually moving from lowest to highest speed until it's light and creamy and the salt has been whipped in.
Use a spatula to remove the butter from the whisk and bowl and transfer it to a clean container or jar. This should yield you around 200g of butter from 600 mls of cream.