Sterilise a lidded jam jar, jelly bag or sieve, spatula and measuring jug. Set aside for the end

Put all the ingredients except the eggs into a saucepan over a low heat. Stir until the butter is melted and the sugar has dissolved

Transfer the mixture to a heatproof bowl and allow the contents to cool slightly (about 5 minutes)

In the meantime, bring a saucepan of water to a simmer (ensure the heatproof bowl can sit on top of the saucepan without the water coming into contact with the base)

Add the eggs to the mixture and put the heatproof bowl on top of the saucepan of simmering water

Stir occasionally until the mixture thickens to the consistency of custard (about 45 minutes)

Pour the mixture through the sterilised jelly bag/sieve into the measuring jug. Push the contents through using the spatula, if necessary

Transfer the curd into the sterilised jar and cover immediately with the lid. Allow to cool completely before using