Crush Oreos in a processor and add melted butter. Place in tray and flatten. Set in fridge until the next step it ready.

Make a water-bath. In another pot, add chocolate and 1/2cup whipping cream. Place over the water bath and mix until it is melted.

In the meantime, add gelatin to water and allow to sit for 5-10minutes.

When chocolate mixture is melted, remove from heat and place gelatin on the water-bath until the gelatin has melted. Then pour into the chocolate mixture and allow to cool.

Beat the remaining 2/3cup of whipping cream until stiff peaks and pour the above mixture in and mix until combined.

Pour the mixture over the Oreo Base and allow to set in the fridge for 20-30minutes.

When the first layer is set, follow the same process to make the next layer of mousse.

Allow to set in the fridge overnight or for at least 4hours.

Demould and decorate as desired.