Preheat the oven to 160°C (140°C fan-forced). Line two large oven trays with non-stick baking paper.
For the whipped chocolate cream, place the chocolate in a medium bowl. Combine the cream and water together in a small saucepan over a medium heat and bring to a simmer. Remove from heat and pour over chocolate, stirring until combined. Not all the chocolate will melt immediately, so stir every few minutes until chocolate is completely melted. Allow to cool, before covering with plastic wrap and refrigerating for 2 hours or overnight.
For the pavlovas, place the egg whites in a large bowl and beat until soft peaks form, using electric beaters. Gradually add sugar, 1 tablespoon at a time, beating until it dissolves between each addition. Once all the sugar has been incorporated and has dissolved, add the cornflour, cocoa, vinegar and 50g chopped chocolate, folding gently to combine.
Evenly divide the meringue mixture into 8 and spoon onto prepared trays.
Place pavlovas in preheated oven and immediately reduce the temperature to 120°C (100°C fan-forced). Bake for about 40 minutes or until dry to touch. Turn oven off and cool pavlovas in the oven, with the door ajar.
When ready to serve, whip cream mixture with an electric beater until light and fluffy. Carefully place the meringues on serving plates using a spatula. Divide the chocolate cream between the meringues, top with diced strawberries and sprinkle with remaining chocolate to finish.