Soak gelatine in cold water. Separate eggs. Beat the egg yolks, sugar, vanilla sugar, lemon zest and rum with the whisks of the hand mixer until thick and creamy white (ten minutes). Squeeze the gelatine, dissolve carefully and stir into the egg cream. Chill for six to eight minutes until the cream begins to gel.
In the meantime, beat the egg whites with salt and whipped cream until stiff. Carefully fold in first the cream, then the beaten egg white. Pour into a bowl and chill for two hours. Dust with cocoa. Serve decorated with cream, biscuits and mint
With 10 people: