Chocolate Sandwich Cheesecake

• Preheat your oven to 200℃, do not use fan heated

Chocolate Biscuit Base

• Over a low heat, gently melt the butter with the cocoa and sugar, stirring until smooth and glossy. Remove from the heat, then stir in the coffee.
• Crush the biscuits into fine crumbs using a food processor. Alternatively, place them in a sealed plastic bag and crush with a rolling pin.
• Pour the melted chocolate mixture over the biscuit crumbs and stir until thoroughly combined.
• Lightly oil a 23cm (9in) springform tin. Spoon in the biscuit mixture, pressing it firmly and evenly over the base and up the sides of the tin.
• Bake for 8–10 minutes, or until firm. Set aside to cool.
• Increase the oven temperature to 220°C.

Cheesecake Filling

• Melt the chocolate in 15 sec increments in the microwave, set aside to chill
• Using a wooden spoon, gently mix the mascarpone, cream cheese, sour cream, cornflour and vanilla until smooth and creamy.
• Separate the eggs, then add the egg yolks to the cheese mixture and stir gently until combined.
• Add the double cream to the cheesecake mixture and gently mix until incorporated.
• Add in the chilled chocolate, mix.
• In a clean bowl, whisk the egg whites, gradually adding the caster sugar, until soft peaks form. Gently fold the whipped egg whites into the cheesecake mixture, taking care not to knock out too much air.
• Pour the filling over the cooled biscuit base and loosely cover the tin with foil.

Bake the cheesecake

• Place a wide ovenproof pan filled with water on the bottom shelf of the oven. Place the cheesecake on the middle shelf and bake for 12–15 minutes, until the top and edges are lightly golden and beginning to set.
• Remove the cheesecake from the oven and reduce the temperature to 170°C. Allow the oven temperature to drop before returning the cheesecake to the middle shelf. Bake for a further 40 minutes.
• The cheesecake is ready when the edges are firm and set but the centre still has a gentle wobble.
• Turn off the oven and leave the cheesecake inside for 1 hour, with the oven door slightly ajar. Remove it from the oven and leave to cool at room temperature for a further 1 hour.

Chocolate Ganache

• Gently warm the double cream in a saucepan over a low heat. Add the dark and milk chocolate and stir until completely melted and smooth. Remove from the heat, add the butter and stir until glossy.
• Transfer the ganache to the fridge and chill for approximately 20 minutes.
• Remove from the fridge, add the icing sugar and whisk for 2–3 minutes, until light, soft and fluffy.
• Once the cheesecake has cooled completely, carefully remove it from the tin and generously spread the whipped chocolate ganache over the top.
• Refrigerate the finished cheesecake overnight before serving. This allows it to set fully and gives the flavours plenty of time to develop.