Place the blackcurrants in a small saucepan with the granulated sweetener and 1 tbsp of the water.
Cover the saucepan with a lid and place over a low heat. Gently cook for 10 minutes, until the blackcurrants have burst open and have softened.
Place a nylon sieve over a medium mixing bowl. Pour the cooked blackcurrants and cooking juices into the sieve.
Using a wooden spoon, push the blackcurrants and juices through the sieve into the bowl. Discard the blackcurrant skins and pips left in the sieve.
You should now have 100ml of blackcurrant syrup in the bowl. Allow to cool.
Once cooled, stir in the yoghurt until completely combined with the blackcurrant syrup.
Heat the remaining 1 tbsp water until it is hot, but not boiling and place in a small cup. Sprinkle on the gelatine and stir until dissolved. You can stand the cup in a small bowl of hot water to help the gelatine to dissolve if needed.
As soon as the gelatine has dissolved into a clear, lump free liquid, immediately pour it into the blackcurrant and yoghurt mixture. Whisk with an electric whisk, on the high setting, for 4 - 5 minutes, until thickened and frothy.
Pour into 4 x 300ml serving dishes and place in the fridge for 2 - 3 hours until set.
Decorate with a few fresh blackcurrants if wished, and serve at once.