How to Make It
Cream together the butter, sugar, eggs, and juice with a hand or stand mixer. It'll look a little separated at this point, but that's OK.
Transfer the mixture into a small to medium saucepot over low heat.
Let the mixture warm slowly over low heat, and stir it frequently. For me, the curd usually comes together in about 7 to 10 minutes, but your cooking vessels and stovetop may vary slightly. The curd is done when it's thickened to the point that it coats the back of a spoon.
Transfer the curd to a jar or bowl, stirring occasionally to allow steam to escape. If flecks of egg white appear, strain through a fine mesh strainer to remove them.
Let cool in the refrigerator for at least an hour. The curd will thicken further as it cools.
Enjoy on toast, scones, over ice cream, or just by the spoonful. Curd!