Nigella Feasts: Chocolate Cheesecake

Recorded from watching the episode

Ingredients

Base
1 1/3 cup (125g digestive biscuits) graham cracker crumbs
1 tbsp cocoa
1/2 stick butter (50-60 g)

Filling
2 packets of Philly (500g) which must be at room temperature in order to get the satiny smoothness
3/4 cup (150g) superfine or caster sugar
1 tbsp custard powder (this can be substituted with 1 tbsp cornstarch, 1 tsp sugar, 1 tsp vanilla)
3 eggs
3 yolks
2/3 cup (150ml) sour cream
1 tsp cocoa dissolved in 1 tbsp hot water from a kettle
175g (6 oz) melted bittersweet chocolate, let it stand so that it isn't too hot

Topping
3/4 bar bittersweet chocolate, melted

Method
1) Put the digestive biscuits into a freezer bag. Use a roller pin to bash up the biscuits into find crumbs.
2) Add the crumbs to a mixer and give it a quick whirl to ensure no larger crumbs remain.
3) Add the cocoa and whirl again to ensure its evenly distributed. Do the same with the butter. Whirl until the crumbs look like damp clumpy sand.
4) Pour it into the cake tin and use your knuckles to form the base. Press down with your hands because the heat from your hands helps the butter to melt and adhere. Stash in the freezer for a few minutes just to chill it.
5) In a fresh clean mixing bowl, add the cheese and whirl slightly.
6) Add the sugar and custard powder. Crack in the eggs and add the egg yolks. Pour in the sour cream. Add in the cocoa solution. Give everything a whirl. It should be quite runny which makes it smooth.
7) Fold the melted chocolate into the cheesecake mixture, slowly and patiently until evenly blended.
8) Retrieve the base from the freezer. Wrap the exterior of the cake tin with cling film, covered on top by aluminum foil. Pour the cheesecake filling on top of the base.
9) Place tin into a roasting tin. Pour a kettle of recently boiled water into the roasting tin so that the water level comes halfway up the cheesecake tin. The cake tin may wobble a bit due to the buoyancy of the flim.
10) Bake in a 350 deg F (180 deg C) oven for 45 mins to 1 hour. It is ready when it has just set. It should set properly at the sides and just wobble in the centre.
11) Once ready, remove carefully from cake tin. Drizzle the topping on top of the cheesecake.