01 - In a heatproof bowl, vigorously whisk together the eggs and granulated sugar until fully blended and smooth.
02 - Incorporate the lemon zest and freshly squeezed lemon juice into the mixture, stirring until consistently combined.
03 - Place the bowl over a saucepan with gently simmering water, ensuring the bowl does not touch the water’s surface.
04 - Continuously whisk the mixture over gentle heat for 8 to 10 minutes, until it thickens and coats the back of a spoon.
05 - Remove from heat and immediately whisk in the cubed unsalted butter until fully melted and the curd is smooth.
06 - Pour the lemon curd through a fine-mesh sieve into a clean bowl to eliminate bits of zest or cooked egg, achieving a silky texture.
07 - Allow to cool completely, then transfer to sterilized jars. Refrigerate and use within 2 weeks.