- finely grated zest and juice of 4 lemons
- 6 egg yolks
- 125g caster sugar
- 180g soft unsalted butter
1 Combine the zest, juice, yolks and sugar in a heatproof bowl and set over a saucepan of barely-simmering water. Cook, whisking constantly, for 5 minutes, until the mixture thickens, then remove from the heat.
2 Whisk in the butter, 1 Tbsp at a time, until the mixture is smooth. Store refrigerated.