1. With the electric mixer whip the double cream until it forms soft peaks. Add Greek yoghurt and 2 tablespoons of caster sugar and whisk for a few seconds more until smooth.
2. Roughly break up two meringues and gently fold them into the mix. Set aside.
3. In the small mixing bowl place most of blackberries (leaving a few for decoration) and crush them with a fork.
4. Carefully add the crushed fruit into the mix, gently folding them in, and then carefully spoon into the serving glasses. Decorate with the remaining blackberries.
To serve: Place it in the fridge for 15 minutes before serving. You can of course leave them in the fridge for longer but the crushed meringues will gradually start dissolving into sugar so make sure you have them in larger pieces in the first place.