Place cheesecloth over the jar and secure with rubber band.
In a heavy based pot, melt butter on a medium heat.
Once butter has melted, it will begin to bubble and splutter (watch out!).
The butter will separate into layers. The top layer will be foamy and white, you can scoop this out or leave it there as it will eventually be drained through the cheesecloth.
As the butter bubbles it will become quite constant, then ease off to close to nothing. Once the butter has stopped bubbling your ghee is ready. This process will continue for approx 25 - 30 minutes.
Remove from heat and pour through cheesecloth.
Leave on the bench until it cools completely. You can keep it in your cupboard for around 6 months or in the fridge for 1 year.