Step 1

Line 22cm springform tin with plastic wrap.

Step 2

Process biscuits until fine. Add butter; process until combined. Press mixture over base of tin. Refrigerate 30 minutes.

Step 3

Make filling by sprinkling gelatine over the water in small heatproof jug; stand jug in small saucepan of simmering water. Stir until gelatine dissolves; cool 5 minutes.

Step 4

Beat cheese, sugar and egg yolks in medium bowl with electric mixer until smooth; beat in cream. Stir in dark chocolate and gelatine mixture.

Step 5

Beat egg whites in small bowl with electric mixer until soft peaks form; fold into cheese mixture. Pour filling into tin.

Step 6

Combine white chocolate and extra cream in small jug. Swirl white chocolate mixture through cheesecake mixture. Refrigerate overnight

Step 7

Spread dark chocolate over baking paper to a 20cm square. When set, break chocolate into small pieces.

Step 8

Remove cheesecake from tin to serving plate. Press chocolate pieces around side of cheesecake