Process the deseeded watermelon chunks in the food processor and strain the pulp.
Grind the oreo biscuits in a grinder, add the melted butter and whiz again.
Press 2 tsp each in small glass bowls or small wine glasses to form the bottom layer of the mousse and refrigerate for 10 minutes to let the biscuit layer set.
Beat the chilled whipping cream in a chilled bowl with chilled blades till standing peaks.
Add the soft cream cheese and sugar and beat to mix .
Now add the water melon pulp and mix gently.
If you feel the mousse mix has turned thin add gelatin to hot water and mix well till there are no lumps and add to the mix so that it sets.
Divide the mousse mix and spoon into individual glasses over the biscuit layer.
Cover them with cling film and refrigerate for 3-4 hours or overnight.