Combine the base ingredients and press onto the bottom of a 20cm springform tin.
Chill the base for 30 minutes.
Mix the gelatine with boiling water, stir well, and let cool.
Beat cream cheese, sugar, and salt until smooth.
Add sour cream, gelatine, and vanilla, then beat for three more minutes.
Melt white chocolate in the microwave in 30-second bursts until smooth.
Stir melted chocolate into the cream cheese mixture until smooth.
Pour half the mixture into the tin and sprinkle with half the biscuit chunks.
Add the remaining mixture, smooth the top, and scatter the remaining biscuits.
Refrigerate for at least two hours or overnight until set.
Loosen the cake with a warm knife and remove the outer ring before serving.