Method:
Make mousse, boil custard, cocoa powder, coffee powder, condensed milk and stir it till it boils, remove from flame and cover it, let it cool down.
Mix gelatine in quarter cup hot water.
Crush oreo biscuits, pour on a casserole or individual dessert glasses.
Sprinkle expresso coffee on oreo layer then keep aside.
In custard mixture, pour cream and gelatine mixture and whisk well, pour on oreo layer and level it.
Decorate with oreo biscuits, walnuts and chocolate flakes.