Place biscuits in food processor and pulse until coarse crumbs form. Add melted butter and pulse until the mixture forms into a ball.
Scoop arils from pomegranates into a bowl and drain the juice into a measuring cup. You need 4 tbsp juice. If there is not enough, spoon some of the arils into a sieve over a bowl and use the back of a kitchen spoon to press out more juice. Repeat until there is sufficient juice. Discard solids, set juice aside and reserve un-pressed arils.
Press crumb mix into the base of a 26cm spring form tin and chill for 2 hours.
Beat cream cheese, sugar and vanilla till smooth. Add 100ml cream and beat lightly. Add mascarpone and whip until incorporated.
Over a double boiler, melt chocolate and stir through remaining cream. Stand to cool for 10 minutes.
Fold chocolate, 4 tbsp pomegranate juice and gelatine mix into cheese mix and pour into chilled crumb base. Refrigerate for 4 hours.
Serve sliced cheesecake garnished with reserved arils.