Crush biscuits and mix them with butter.
Cover the bottom of a tin of about 8/ 10 inches and stick in fridge.
Beat cream cheese untill fluffy, add caster sugar and beat again.
Add eggs and yolks one by one still beating then pour in sour cream and lime juice, mix well.
Pour the cream in the tin, add spoonful of melted chocolate and swirl a little with a fork to marblelized the cake.
Bake at 356°F for about 25 minutes or untill the cake is slightly golden on the edges.
Serve it room temperature or cold, store in fridge.