Crush biscuit crumbs and butter. Mix well.
Press into base and sides of deep 23 cm flat tin. Chill until firm.
Pour water into a shallow bowl and sprinkle 1 tbsp gelatine over it. Stand until gelatine swells.
In a saucepan over low heat dissolve gelatine, stirring constantly.
Cool. Drain plums reserving ¼ cup juice. Place drained yogurt, dairy blend, yogurt and plums in food processor or blender and process until smooth.
Add gelatine mixture and process only to mix.
Pour into base. Chill to set.
Decorate with cream.
Remember not to sprinkle gelatine into hot liquids, as it will probably become lumpy.
Never be tempted to add a little extra as you will spoil the flavour and texture.