Combine all ingredients in a saucepan.
Heat on medium heat, stirring constantly, until mixture thickens.
The lemon curd will be ready when the mixture coats the back of a spoon.
When cooked, pour into a bowl and cover with cling wrap pressed onto the top of the curd and refrigerate until cold.
Instead of adding it to a bowl, pour the lemon curd into warm glass jars and seal.
Store in the fridge and consume within 2 weeks.