Biscuit de Savoie

Preheat your oven to 180°C and grease a cake mold with 10g of butter.

Whisk 80g of egg yolks with 60g of sugar and 5g of lemon zest until the mixture becomes pale and thick.

Beat 160g of egg whites until soft peaks form, then gradually add the remaining 60g of sugar until stiff peaks develop.