3 large eggs and 1 egg yolk
200g caster sugar
100g unsalted butter
Crack 3 large eggs into a bowl, and add one more yolk.
Using a fine grater, preferably microplane, grate the zest of the lemons into the eggs. Only take off the very outer layer of the lemons, none of the white pith.
Squeeze the juice of the lemons into the bowl, making sure not to get any pips into the mixture, and then add the sugar.
Place the bowl onto a bain marie and simmer gently, stirring constantly.
Stir for about 5 minutes, until the curd has thickened enough to coat the back of a spoon.
Pour curd through a fine mesh sieve to remove zest and any cooked egg pieces.
Stir through the butter, and then pour into a sterilised jar.
Store in the fridge for up to a month