Also called lemon butter, this is a slightly thick spread that is sweet and lemony.
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.