4 large egg yolks
3/4 c sugar
4 T unsalted butter, softened
Juice of 2 large lemons
2 tsp grated lemon zest
In large sauce pan, beat egg yolks and sugar until well combined. Add softened butter and lemon juice.
Cook over low heat, stirring constantly. Do not allow to boil.
When the consistency is thick, remove from heat and add lemon zest. Place in airtight container and set in refrigerator to chill.