Preheat the oven to 200ºc/180ºfan and get a deep 8"/20cm round tin.
Blitz the biscuits to a fine crumb
Melt the butter in a separate bowl, and then mix into the biscuit. Press the mixture into the bottom of the lined tin.
Bake the biscuit base in the oven for 10 minutes.
Cheesecake
Once the base has been baked, lower the temp of the oven to 180ºc/160ºfan - leave the biscuit base on the side for now.
In a bowl, melt the dark chocolate until smooth - I do this in the microwave in short bursts.
In a new large bowl, add the full-fat soft cream cheese and beat until smooth.
Add the eggs, beating well as you go, and add in the sugars. Beat this until combined.
Add in the cocoa powder and vanilla extract and beat again to combine.
Fold through the cooled melted dark chocolate until smooth.
Add in the double cream, and fold again until smooth. Finally, fold through the raspberries.
Spread the mixture over the baked biscuit base. Bake the cheesecake in the oven for 35 minutes.
Leave the cheesecake to cool in the oven with the door slightly adjar, for an hour
Remove the tin from the oven, and set the cheesecake in the fridge for a minimum of 6 hours.
Decoration
Once the cheesecake has set, add the dark chocolate, milk chocolate and double cream to a jug.
Melt this together and stir well until smooth.
Pour this on to the cheesecake and spread, and sprinkle on some chocolate curls, raspberries and freeze dried raspberries. Leave this to set for about an hour and then portion, and enjoy!
Notes
You can make the base not chocolate-themed by removing the cocoa powder.
I really would recommend using dark chocolate - don't worry, it doesn't taste 'bitter'.
If you want to prevent any cracks in the surface of the cheesecake (it doesn't particularly bother me with this one as I cover the top in ganache) but bake the cheesecake in a bain marie.
Wrap the base of the cheesecake tin foil so water cannot get to it