1/2 cup unsalted butter
1 1/4 cups granulated sugar
1 egg yolk
1 cup fresh lemon juice (about 6 juicy lemons)
lemon zest from 3 lemons (I highly recommend this article, if you haven't read it)
This pic is before heating. It looked foamy from the whisked sugar and the floating bits are the zest.
This is after the straining.
The total made was 3 1/2 pints and a generous amount left to sample.
I will definitely be reusing this recipe.