Combine the eggs, egg yolks and sugar in a mixing bowl and beat until smooth.
Add the lemon juice and lemon zest and mix.
Place the bowl over a pot of boiling water or in the top of a double boiler and stir vigorously with a wooden spoon until the mixture thickens. This mixture will not curdle, so don't worry about overcooking it a little.
Remove the bowl from the boiling water and stir in the butter until melted.
Notes[]
Refrigerated, this will keep for up to 3 months.
Traditionally served in Britain with crumpets, scones, in tarts and jelly rolls.