Line a slice tin with baking paper, leaving enough so the sides overhang.
Crush the chocolate ripple biscuits until they are finely crumbed. Add the melted butter and mix together. Pour mixture into slice tin and using the back of a metal spoon, push the mixture evenly over the base of the tray. Place in the fridge for half an hour to cool.
Place the hot water into a small bowl, and sprinkle the gelatine over the top. Place in microwave and heat for 20 second bursts, mixing in between until the gelatine has dissolved. Set aside to cool.
Using an electric mixer, beat together the cream cheese, cream and sugar until smooth. Add the gelatine mixture (you want it to be a similar temperature to the cream cheese mixture, otherwise it will go lumpy) and beat together. Once combined, add the melted white chocolate and mix together.
Add ¾ cup of frozen raspberries to cream cheese mixture and carefully fold through. Pour over the chilled biscuit base and decorate the top with remaining raspberries.
Drizzle the dark chocolate over the top of the cheesecake slice.
Put the slice into the fridge for six hours (preferably overnight) to set, then cut into squares to serve.