Make the filling by adding cream cheese, icing sugar and vanilla extract to a large bowl. Whisk together using an electric whisk until combined.
In a separate bowl whisk the double cream until thickened. Add the thickened double cream mixture to the cream cheese mixture and whisk until just combined. Stir through the finely chopped cookies and cream biscuits.
Spoon the filling onto the biscuit base and smooth the top with a knife. Chill in the fridge for at least 4 hours or ideally overnight.