Put the butter, sugar, and the lemon zest and juice into a double boiler, or into a bowl set over a saucepan of barely simmering water. Stir the mixture with a wooden spoon until the sugar has completely dissolved.
Remove the pan from the heat and strain in the beaten eggs. Replace the saucepan over a low heat and stir the contents until the mixture thickens and coats the back of the wooden spoon. Pour into warm sterilized jars and seal.
© 1999 Jennifer Paterson and Clarissa Dickson Wright estate. All rights reserved.