Preheat the oven to 140°C / 275°F / Gas mark 1.
Line a large, baking tray with greaseproof paper and set aside.
In a large spotlessly clean bowl, place the egg whites with a pinch of salt.
Whisk until the egg whites hold soft peaks.
Add the sugar, 1 tablespoon at a time, whisking well between each addition, until it is thick and glossy, and will hold up in stiff peaks on the end of the beaters or a whisk.
Fold in the vinegar and cornflour.
Using a large spoon, pile the meringue onto the baking tray, then spread to a rectangle.
Use the back of the spoon to make peaks and dips in the meringue to make it attractive.
Bake in the centre of the oven for 1 hour 20 minutes, then turn off the oven and leave it inside the tray to cool overnight.
Just before serving, softly whip the cream, then fold through the yoghurt and rose water, if using.
Remove the Pavlova from the greaseproof paper and place on a large serving plate or board.
Dollop the vanilla cream on top, then top with the cherries. In a bowl over simmer water, melt half of the chocolate to a sauce consistency then drizzle over the entire dessert.
Use the rest to decorate, made into shavings from a knife or grater.