In a saucepan melt three tablespoons of butter, with four heaping tablespoons of sugar and three tablespoons of finely, chopped, lemon zest. Melt slowly over low heat, stirring often, until creamy and pulling away from the sides of the pan.
Set the mixture aside to cool off. While it is cooling, whip until frothy two egg whites.
Add two egg yolks to the cooled-off, butter-sugar mixture, stir until smooth and creamy. Then add the juice of two lemons (A cup's worth at least.) and continue to stir often over low heat. Add the egg whites, keep stirring over low heat. Do not boil.
At the last minute I added a few tablespoons of cream. Eventually, the lemon mixture starts to thicken and seems to double in size. Turn off the heat.
I used puff pastry dough, because the French grocery stores have the best ever selection of ready made pie doughs... and they are flaky perfection without the stress.
Cut the puff pastry into small rounds, I used a juice glass. Then in a cupcake pan, I put parchment paper and pressed the round puff pastry dough into place. Next I added a heaping tablespoon of the lemon mixture onto each round. (Makes 12 Lemon Tarts.)
Bake in a preheated oven at 350 for five minutes.