Lemon butter or lemon curd is perfect to garnish tarts or biscuits but is also good simply spread on good bread. It will keep a couple of weeks in the fridge.
In a bowl, combine the eggs, sugar and lemon juice. Place over a saucepan of simmering water, making sure the bottom of the bowl does not contact the water. Whisk for about 10 minutes until thickened.
Remove from the heat and strain through a sieve to remove any lumps. Add butter and whisk until the butter has melted. Lastly, beat in the lemon zest.
Pour into sterilised jars and seal, let cool and store in the fridge.