Grease and flour oven tray, mark 21cm circle on tray. Beat egg yolk and sugar in small bowl with electric mixer until thick, add essence. Beat egg white in a small bowl until soft peaks form, beat in extra sugar, beat until dissolved.

Fold sifted flour into egg yolk mixture, gently fold in egg white mixture.

Spread mixture onto prepared tray, using circle as guide. Bake in moderate oven about 10 minutes or until sponge is cooked through. Turn sponge layer onto wire rack to cool. Trim sponge layer to fit into 20cm springform tin.

Pour lime bavarois over sponge layer in tin, cover, refrigerate about 2 hours or until firm. Pour passionfruit jelly over lime bavarois, cover, refrigerate several hours or overnight.

Beat egg yolks and sugar in small bowl with electric mixer until thick and creamy. Heat milk in pan, bring to boil. Gradually beat hot milk into egg yolk mixture while motor is operating.

Pour mixture into pan, sir over low heat, without boiling, until custard mixture is slightly thickened. Stir in rind and 1/3 cup of the lime juice.

Sprinkle gelatine over remaining juice in cup, stand in pan of simmering water, stir until dissolved; pour into lime mixture; cover, cool, refrigerate 1 hour or until mixture is almost set.

Beat cream in small bowl until soft peaks form, gently fold into lime mixture. Pour over sponge layer, refrigerate several hours.

Remove pulp from passionfruit. Strain pulp, reserve juice snd seeds; you will need 1/2 cup juice and 1 tablespoon seeds.

Combine reserved juice and seeds in pan, add water and icing sugar. Bring to boil, remove from heat, add gelatine, stir until dissolved. Cool to room temp then pour over Bavarois and refrigerate several hours or overnight.