Crush the biscoff biscuits, either in a sandwich bag with a rolling pin, or blitz in a blender. Place into a bowl and add the melted butter, mixing until combined.
Transfer the biscuit mixture to your prepared cake tin and evenly push it down to cover the bottom of the tin, packing it right down. Place in the fridge while you prepare the filling.
In a large bowl, mix the cream cheese, biscoff spread and icing sugar until combined.
In a seperate bowl, whip the double cream until it forms stiff peaks. Add the cream to the other filling ingredients and gently fold together until combined.
Spoon the filling into your cake tin, on top of the base, spreading to the edges and leaving a neat top.
Return to the fridge to set, ideally overnight but for at least 2-3 hours. Decorate with drizzled biscoff spread and crushed biscuits before serving.
Notes
To make it easier to drizzle the biscoff spread when decorating, blast the spread in the microwave first.