Crush the cookies in a plastic bag or in a food processor until they resemble fine breadcrumbs; transfer to a mixing bowl. Melt the butter and add it to the crushed cookies mixing until well combined. Spoon the cookie crumbs into the base of a 20cm springform tin and press down with the back of a spoon to compact. Place in the fridge to chill.
For the filling:
Meanwhile, mix the gelatine with the cold water and set aside for a few minutes to soak.
In a separate bowl mix the cream cheese with icing sugar and crushed biscuits.
Place the gelatine in a pan over a low heat for 2 to 3 minutes until it starts to melt. As soon as it has melted add it to the cream cheese mixture and mix thoroughly to combine. Remove the base from the fridge and spoon the cream cheese filling on top. Place in the fridge to chill for 2 to 3 hours until set.
For the decoration:
Mix the gelatine with the cold water and set aside for a few minutes to soak. Place the gelatine in a pan over a low heat for 2 to 3 minutes until it starts to melt.
In a food processor, blend the orange slices and then stir in the gelatine. Pour the mixture over the top of the cheesecake then return to the fridge to set, about 2 to 3 hours or overnight. Once set, slice and serve.