To make the base, line a deep 20cm springform tin with baking parchment, then blitz the biscuits and walnuts to a fine crumb in a food processor or blender. Tip the crumbs into a heatproof bowl. Melt the butter in a pan over a low heat, then stir this in to create a wet, sandy texture. Tip the mixture into the prepared tin and press it into the base. Put in the fridge to chill while you make the filling.

For the filling, dissolve the espresso powder in 2 tbsp warm water. Put the soft cheese, icing sugar, vanilla and coffee in a bowl and whisk until smooth. Pour in the double cream and whisk everything together until the mixture has thickened. (Alternatively, you can whisk the double cream to soft peaks in a separate bowl, then fold this into the cheese mixture.) Spread the filling over the biscuit base using a spatula, pushing down gently as you do to ensure there are no gaps. Put in the fridge to chill for at least 6 hrs, or ideally overnight.

To decorate, whip the double cream and icing sugar to soft peaks, then spoon into a piping bag fitted with a star nozzle. Pipe swirls over the cheesecake, then top each swirl with a walnut. Crush any remaining walnuts and scatter over, if you like. Will keep chilled for up to two days.