Take butter in a saucepan and melt it down.
Now take oreo cookies it in a Blender and powder them.
Take it in a bowl pure in butter and mix well.
Spoon this into the serving dish and smoothen evenly.
Now melt white chocolate and butter in a microwaven.
Now pour this over the mousse and set it in fridge for 4 to 5 hours.
Then frost the cake around the site oreo cookies and top some Cherry.
Then serve yummy Oreo Chocolate Mousse cake.