Meanwhile, make the lemon curd
In a glass bowl, combine the egg yolks, lemon juice and sugar and whisk until smooth. Place the bowl over a saucepan of simmering water (do not let the bottom of the bowl touch the water) and cook, whisking constantly, until the curd has thickened to the consistency of cake batter, about 20 minutes. Remove the bowl from the heat and whisk in the butter, a few cubes at a time, until incorporated. Press plastic wrap directly onto the surface of the lemon curd and let cool to room temperature. Refrigerate for 1 hour, or until cold.