Rub the lemon zest with the sugar between your fingers to allow the sugar to absorb the essential oils from the zest
Add the 2 eggs and lemon juice and whisk until well combined
Pour the mixture into a small saucepan and cook over very low heat, stirring continuously, until thickened
Remove from heat and let cool for 5 minutes
Add the 75g of room temperature butter and whisk with a hand blender until light and fluffy
Transfer to a glass jar and refrigerate for at least 1 hour before serving
