Prepare the lemons – Finely grate the zest from the lemons and squeeze out the juice. Strain the juice to remove seeds.

Whisk eggs and sugar – In a heatproof bowl, whisk together the eggs and caster sugar until smooth and slightly pale.

Add lemon juice and zest – Stir the lemon juice and zest into the egg mixture. This creates the base for the curd.

Prepare the saucepan – Place a small saucepan with a little water on the stove and bring it to a gentle simmer. Set the bowl over the pan to create a double boiler.

Add butter gradually – Cut the butter into small cubes and add them to the mixture.

Cook gently – Stir continuously over gentle heat for about 10–15 minutes until the mixture thickens.

Check the consistency – The curd is ready when it coats the back of a spoon.

Cool and store – Pour the curd into a sterilized jar and allow it to cool completely before sealing.