Whisk all ingredients together in a small saucepan, and cook over medium heat.
Continue to heat, whisking constantly until curd is thickened - about 3-5 minutes. Do not allow to boil.
Strain the curd through a fine strainer, removing any solids.
Refrigerate until cold and thick, around 3 hours, before using.
Devour.
Notes
Can you use bottled lemon juice? Unfortunately, no. Using fresh lemons is key for this - the stuff in the bottle just will not cut it!
How to store lemon curd - seal in a plastic container or jar with a lid (or tightly covered with plastic wrap). It will keep for about a week in the refrigerator!