Combine biscuit crumbs, sugar and butter then press into a greased 26 cm (10") springform pan; chill for 20 mins.
Pour water over raisins and leave to stand.
Beat PHILADELPHIA cream cheese and sugar using an electric mixer until smooth. Add rum (optional), melted CADBURY OLD GOLD chocolate, vanilla and salt and beat until smooth.
Beat in eggs and yolk, one at a time, until well combined. Drain raisins and fold into mixture.
Pour mixture into prepared OREO cookie base and bake at 160 °C for 45-50 minutes, or just set. Allow to cool completely in oven with door ajar. Once cooled chill for 2 hrs or until set.
Roughly chop CADBURY OLD GOLD chocolate and scatter over Cheesecake with extra raisins.