Preheat the oven to 180˚C (160˚C fan oven, 350˚F, gas 4). Grease and base line a 6.5cm (2 ½ inch) deep, 20cm (8inch) diameter spring-form cake tin. Double wrap the outside of the tin with foil to make it waterproof.
Put the crushed biscuits in a bowl and mix in the Cocoa Powder and sugar. Bind together with the melted butter, mixing well until thoroughly blended. Pile into the prepared tin, and press evenly into the tin using the back of a spoon to cover the base. Chill until required.
Now make the filling. Break the Extra Dark Chocolate into pieces and place in a heatproof bowl. Place over a saucepan of barely simmering water and leave to melt. Remove from the water, mix well and cool for 10 minutes.
Meanwhile, in a large bowl, mix the soft cheese, double cream and Vanilla Paste together. Mix in the melted chocolate – the mixture will thicken – and then gradually beat in the eggs and sugar.
Spoon over the crumb base and smooth the top. Stand the cheesecake in a roasting tin and pour in sufficient boiling water to come halfway up the side of the tin. Bake in the oven for 1 hour until firm and set. Turn off the oven heat, open the oven door and keep ajar, leave the cheesecake to cool for 30 minutes in the oven.
Remove the cheesecake from the water bath and transfer the cheesecake, still in the tin, to a wire rack; leave to cool completely. Carefully remove the cheesecake from the tin and transfer to a serving plate. Chill for at least 3 hours – preferably overnight.
To decorate, break the 100g of Extra Dark Chocolate into a heatproof bowl and add the butter and 15ml (1tbsp) cold water. Put the bowl over a saucepan of barely simmering water and leave to melt. Remove from the water and leave aside for about 20 minutes or until it begins to thicken slightly.
To serve, stand the cheesecake at room temperature for 10 minutes then spoon over the chocolate sauce, gently spreading and allowing it drip over the edge of the cheesecake. Pile the centre of the cheesecake with dark chocolate rolls – see below. Your cheesecake is now ready to serve and enjoy!
1) Break 75g (3oz) Dr. Oetker 72% Extra Dark Fine Cooks’ Chocolate and 75g (3oz) Dr. Oetker Milk Fine Cooks’ Chocolate into pieces and place in a heatproof bowl. Put the bowl over a saucepan of barely simmering water and leave to melt. Remove from the water and mix well.
2) Spread the melted chocolate over an upturned clean, uncoated (not non-stick) or enamel baking tray or clean board to make an oblong approx. 30 x 20cm (12 x 8inch). Leave in a cool place for a few minutes until almost set – the surface will look dull rather than glossy but still able to retain a fingerprint when ready to use. Line another tray or board with baking parchment.
3) Using a cheese slicer, drag the blade of the slicer across the chocolate to form curling rolls of chocolate – the length and thickness of the rolls depends on how long you drag the slicer into the chocolate. Transfer the chocolate rolls to the tray or board – handle carefully as they will be fragile. Continue scraping the chocolate until it is all used up. Keep the rolls in a cool place to prevent them from melting, until ready to use.