1.Process strawberries in a food processor until smooth. Pour strawberry puree into a bowl.
2.Sprinkle gelatine over 2 tblsp cold water in a small heat-resistant bowl, stand bowl in pan of gently simmering water (or microwave on HIGH about 20 seconds) until gelatine is dissolved, cool to room temperature.
3.Beat egg yolks and sugar in a small bowl with an electric mixer until thick and creamy.
4.Quickly whisk gelatine mixture into pureed strawberries, then add to beaten egg yolk mixture and whisk to combine.
5.Beat 150ml cream with an electric mixer until soft peaks form. Fold whipped cream into strawberry mixture.
6.Line a 15cm round cake pan with enough plastic wrap to cover base and extend over sides of pan. Cut the sponge cake horizontally in half.
7.Place sponge base into lined cake pan. Pour strawberry mixture over sponge base. Gently place sponge top over strawberry mixture. Cover and refrigerate for several hours or overnight until set.
8.Beat remaining cream until soft peaks form. Spread whipped cream over top of cake and decorate with extra strawberries.
Strawberry mousse cake can be prepared a day ahead. Keep covered in the refrigerator. Decorate with extra cream and strawberries just before serving.Note