Rub the lemon zest with the sugar between your fingers to allow the sugar to absorb the essential oils from the zest
Add 2 large eggs and the juice of the lemon
Whisk until everything is mixed well
Pour into a small saucepan and cook over very low heat, stirring continuously with a hand whisk
Keep a close eye on the mixture to prevent it from becoming grainy
Let the mixture cool for 5 minutes
Add 75g of butter cut into pieces (at room temperature)
Whisk with a hand blender to incorporate air and create a light, fluffy, airy texture
Be careful not to whip too much to keep it creamy
Place in a glass jar and refrigerate for at least 1 hour before serving
