This lemon variety has an subtler, almost floral, taste, which makes it the perfect ingredient for the versatile custard. Spread on toast or fill a tart shell for the perfect punch of lemon.
In a mixing bowl, combine the lemon zest, egg yolks, whole eggs, and salt. Beat the mixture until frothy and set aside.
Over medium heat in a large saucepan with sloping sides, whisk together the sugar and lemon juice. Add the butter slices and heat, stirring, until the sugar is dissolved and the butter has melted (about 5 minutes).
Using a measuring cup or a ladle, remove about a cup of the hot lemon juice mixture from the pot and slowly stream it into the egg yolks, stirring constantly to keep the eggs from curdling.
Once all of the hot liquid has been added to the eggs, pour the egg mixture back into the saucepan.
Heat the mixture over medium-low heat, for 5-7 minutes, stirring the entire time.
Remove the pot from the heat once the mixture thickens and lava-like bubbles start to break the surface.
Allow the curd to cool for 10 minutes before transferring it to a clean storage container or glass jar.*
Place a piece of plastic film directly on the surface of the curd, prior to covering, to prevent a skin from forming on the surface.
Cover and refrigerate until completely cold. This curd will keep, refrigerated, for 5 days. Use it to spread on baked breads, to fill baked good, or to top fruits and yogurt.**
*If you notice solid egg in the custard, strain it through a fine mesh sieve as you transfer it into a clean storage container.
For filling a tart shell:
Fill a pre-baked pie or tart shell with the curd. Bake in a preheated 350°F oven for 10 minutes,or until the curd jiggles slightly when the pie tin is shaken. Remove from the oven and allow to cool completely before transferring to the refrigerator to chill fully. Top with whipped cream, if desired.