Place all ingredients in a small sauce pan. Whisk together well. Turn heat to a low simmer and continue to cook and stir occasionally until it starts to thicken.
Be careful to watch this curd as it thickens. It can all of the sudden thicken and you don't want the bottom to burn. So as it starts to thicken, stir more frequently, and then constantly until it reaches its full thickness. The thickness of jelly in a doughnut is a good reference.
After it is done, remove from heat. Let cool for 20-30 minutes at room temperature. Then finish cooling in the refrigerator.