Preheat the oven to 170 C / Gas 3. Grease a 21cm springform pan, and line with baking parchment.
Melt the butter in a saucepan on a low heat. Whilst it is melting, crush biscuits (great stress relief this XD) until they resemble crumbs. Add the biscuits to the butter and mix until they are thoroughly coated. Place the base mixture into the tin and press down with the back of a spoon until it is spread evenly and well compacted. Place the tin into the fridge to chill whilst you are preparing the filling.
Melt the chocolate gently in a heatproof bowl placed over a saucepan on steaming hot water, leave over the heat, stirring occasionally, until it is a smooth paste. Stir the zest into the chocolate.
Put the cream cheese, eggs and sugar into a food processor and process until thoroughly mixed. Add the cream and process again until just mixed. with the machine running, add the melted chocolate and orange juice through the feed tube and process until smooth. Pour the filling over the crust and smooth the surface.
Bake in the oven until firm on top with a lovely dark glaze, about 45 minutes. Turn the oven off and let the cheesecake cool in the oven with the door ajar. When completely cold, chill overnight.
Take the cake out of the pan and decorate the top with melted Terry's Chocolate Orange. You can do this either with a fork or a piping bag made out of greaseproof baking paper. Finish off with segments of Terry's Chocolate orange, curls of orange zest and chocolate shavings in the centre.
This cake should be kept in a covered container in the fridge and will last for up to 5 days or a month in the freezer.
If you want to make this cake for a dinner party, orange sorbet is a great accompaniment, decorated with angelica or a sprig of mint.
I think I've done everything correctly but the top of the cheesecake has cracked and I have a fan assisted oven but still cooked at 170 is this correct? I'll have to chill and top it to make sure it's correct I hope so as it does look delicious - 13 Mar 2014