2tablespoonsof lemon zest (you can omit this if you want or use less)**from about 2 lemons
Instructions
In a medium size bowl, whisk together 4 egg yolks and 2 eggs.
In the top of a double boiler, combine sugar and lemon juice. Put water in the bottom of the double boiler and bring to a simmer.
Add the whisked eggs to the sugar/juice mixture and set the top part of the double boiler over the simmering water. Stir constantly until mixture thickens and coats the back of a spoon. This should be done slowly, which is why the double boiler helps. If you cook lemon curd too fast it can taste eggy. The stirring process should take 8 to 10 minutes.
Remove pan from heat and pour it into a sieve set over a bowl. Push it through. Add butter one cube at a time, stirring after each cube, until mixture is smooth. Add the lemon zest. Let cool completely before serving.
Notes
Taste the lemon curd before adding the zest. Depending on how lively your lemon juice is, you may not need the zest or you may just want to use less of it.