How to Make It
Whisk together first 3 ingredients in a heavy, nonaluminum, medium saucepan. Whisk together egg yolks, milk, and lemon juice in a bowl; whisk into sugar mixture in pan over medium heat. Bring to a boil, and boil, whisking constantly, 1 minute. Remove pan from heat; stir in butter, lemon rind, and vanilla extract until smooth.