Place caster sugar into mixing bowl and mill 20 sec/speed 10. Transfer into small bowl and set aside.Place chocolate into mixing bowl and grate 10 sec/speed 7. Scrape down sides of mixing bowl with spatula.Melt 2 min/37°C/speed "Gentle stir setting" . Transfer into a small bowl and set aside. Thoroughly clean and dry mixing bowl.Preheat oven to 120°C. Line a baking tray (30 x 40 cm) with baking paper and set aside.Insert Butterfly. Place egg whites, cream of tartar and salt into mixing bowl and whip 2-3 min/70°C/speed 3.Add vanilla and mix 2 min/70°C/speed 3, slowly adding reserved caster sugar through hole in mixing bowl lid.Further whip 5 min/70ºC/speed 3.Remove Butterfly. Add melted chocolate and with aid of spatula, swirl through meringue. Place dollops of meringe onto prepared tray (this should make around 20 medium individual meringues).Bake (120°C) for 15 minutes. Turn oven off and leave to cool in oven.Serve with whipped cream and berries.