1 Rinse blackberries and put 150 g (approximately 2/3 cup) in a tall vesssel.
2 Add half of the yogurt and puree with an immersion blender. Season to taste with sweetener.
3 Spread mixture into 4 glasses.
4 Sweeten remaining yogurt to taste with sweetener and pour into the glasses. Arrange remaining blackberries on top.
5 Chop pistachios coarsely and mix with honey. Sprinkle over parfaits and serve.