Heat the oven to 200C/180C fan/gas 6. Butter a 23cm springform tin and line the side with baking parchment. Blitz the biscuits and pistachios to fine crumbs in a food processor. Tip the mixture into a bowl, then add the pastry and the melted butter, and mix well. Press the mixture into the base of the tin and bake for 10 mins. Leave to cool while you make the filling.

Rinse out the food processor, then tip in the soft cheese, pistachio crème, sugar, vanilla, flour, eggs and soured cream. Blitz until the mixture is smooth and a consistency similar to double cream. Put the cheesecake base on a baking tray to catch any unwanted drips escaping the tin, and carefully pour the cheesecake mixture over the base.

Reduce the oven temperature to 160C/140C fan/gas 3 and put the cheesecake on the middle shelf, then bake for a further 45 mins. After this second bake, turn off the oven, and leave the cheesecake to cool inside with the door closed for 1 hr – don’t be tempted to peek, or the cheesecake may crack. Open the oven door after this time and leave it ajar for another hour (you can use a wooden spoon propped in the door to keep it slightly open). Cool for a third hour at room temperature, then cover and chill overnight.

To make the topping, heat the double cream in a heatproof bowl in the microwave in short bursts or in a small pan over a low heat until just steaming. Put the dark chocolate in a heatproof bowl, pour over hot cream and let stands for a few minutes, then stir to make a smooth ganache. Carefully pour this over the cheesecake layer and quickly spread to the edge before it sets. Sprinkle the extra pistachios and kataifi pastry around the edge. Chill the for at least 30 mins, then remove from the tin and carefully peel off the parchment before serving. Will keep chilled for up to five days.