Ingredients

6 large egg yolks 

Zest of 2 lemons 

1/2 cup freshly squeezed lemon juice (about 4 lemons) 

12 tablespoons sugar 

1/2 cup (1 stick) unsalted butter, cold, cut into pieces 

Preparation

Prepare an ice bath fitted with a medium bowl; set aside. Whisk together yolks, zest, juice, and sugar in a small saucepan. Set over medium heat, and stir constantly with a wooden spoon. Cook until mixture is thick enough to coat the back of the wooden spoon, 5 to 7 minutes.

Remove pan from heat. Add butter, 1 piece at a time, stirring until incorporated. Pass through a fine mesh sieve into prepared medium bowl. Stirring frequently, let stand until cool.

Place a sheet of plastic wrap directly on surface of curd to prevent skin from forming; wrap tightly. Refrigerate until firm and chilled, at least 1 hour.