Zest the lemons.

Juice lemons and add to a small saucepan.

Add sugar, egg yolks, and zest.

Cook over low heat ~10 minutes. (You can also use a double boiler, or boil water in a larger saucepan and cook in that.)

Let cool to room temperature. Remove to a smaller container and chill in the refrigerator.

This lemon curd can be used as a filling for French Macarons.