Add all ingredients to a small pot and warm over medium heat, whisking frequently until the mixture thickens. It will take 5-10 minutes.
It will still be quite thin and runny when warm, which is perfectly fine and you can serve it immediately if desired.
For a thicker curd, refrigerate it for a few hours or overnight.
Serve over biscuits, scones, pancakes, waffles, french toast, regular toast, english muffins, in crepes or as a layer in lemon cake.
