Grease and line a 28cm loaf pan with plastic wrap, leaving plenty overhanging the sides. Place the biscuits in a food processor and whiz to crumb. Add butter and whiz to combine. Press chocolate crumb into the base of the pan and chill until needed.

Wipe out food processor, then drain cashews and add to processor. Whiz until smooth. Add sugar and cream cheese, and whiz to combine. Add strawberries and vanilla, then whiz until smooth and combined.

Soak 4 gelatine leaves in a bowl of cold water for 5 minutes to soften. Meanwhile, place white chocolate in a heatproof bowl. Place cream in a saucepan over medium heat and bring to just below boiling point. Squeeze excess water from gelatine and add to cream, stirring until melted and combined, then pour the cream mixture over white chocolate and set aside for 30 seconds. Stir until melted and smooth. Cool to room temp then add white chocolate mixture to strawberry mixture and whiz to combine. Pour strawberry mixture over chocolate base, then chill in the fridge for 4 hours or overnight until set.

When the mixture has set, soak remaining 2 gelatine leaves in a bowl of cold water for 5 minutes to soften. Place sour cream in a saucepan over medium heat, stirring until smooth and warmed through. Squeeze excess water from gelatine and add to the sour cream, stirring until melted and combined. Cool mixture to room temp, then pour evenly over strawberry layer. Freeze for 10 minutes, then chill for 1 hour or until set.

Slice cheesecake into generous bars using a warm knife.