This tasty lemon curd can be served with Coconut Swiss Meringue Buttercream and Meyer Lemon and Cream Cheese Pound Cake.
Whisk together eggs, egg yolks, sugar, and lemon zest in a heatproof bowl set over a pan of simmering water. Whisk in lemon juice. Cook, whisking occasionally, until mixture thickens enough for whisk to leave a trail, 30 to 35 minutes.
Prepare an ice-water bath. Remove bowl from heat, and whisk in butter, a few pieces at a time. Pour through a fine sieve into another bowl. Place a piece of plastic wrap directly on surface of lemon curd to prevent a skin from forming. Set bowl in ice-water bath, and let cool completely. Refrigerate in an airtight container overnight (or up to 1 week).