To crystalise the rose petals
It's best to do this the day before if possible to allow the rose petals to dry. Separate the petals out on a baking tray. Paint or dip each petal with some egg white and then dip in a bowl of caster sugar ensuring that the whole petal is coated with sugar. Place on a wire rack to dry. Repeat this process until you have enough petals to decorate your Pavlova. Leave the petals to dry overnight somewhere dry and warm. Once dry you can place them in an airtight container. They will be fine for at least a week and maybe longer.
To make the meringue
Line 2- 3 baking sheets with greaseproof paper. On one baking sheet trace around a 8 in circle. On another baking sheet trace around a 6 inch circle. On the final baking sheet trace around a 4 inch circle.
Preheat oven to 140 C. Separate the egg whites into a large clean bowl. Add a pinch of salt and then using an electric hand whisk beat the egg whites until stiff. Now add the sugar a spoonful at a time, beating well after each addition. The egg whites should become very glossy and stiff. After the last spoonful of sugar continue to beat for another 3-4 minutes. Add the cornflour, white wine vinegar and vanilla and using a large metal spoon fold in carefully.
Using a piping bag or just a large spoon place some of the meringue mixture in each of the circles and spread out into a flatish disc. The meringue will rise in the oven, but try not to flatten it too much so that you get a nice shape. Place the meringues in the oven and bake for about an hour. You will know when they are ready as they will lift off the paper quite easily. If they don't lift off the paper then place them back in the oven for a further 15 minutes. Once baked leave to cool on a wire rack. You can bake the meringues up to 2 days before but you will need to keep them in an airtight container.
To make the filling
Place the whipping cream in a large bowl. Using an electric whisk, beat the cream adding a little sugar at a time until the cream is just holding soft peaks. Add the Greek yoghurt and the rose syrup and mix very gently. Leave to sit in the fridge for a few minutes while you prepare the fruit.
Wash the fruit and place on a tray which has been lined with paper towels. Hull the strawberries and cut into quarters if they are very large.
To assemble the Pavlova
Select a serving plate large enough to hold the base meringue. Place the largest meringue on the plate and pile some of the rose cream in the centre, allowing the cream to flow out towards the edge a bit. Top with fresh fruit. Add a second layer of meringue, followed by the cream and fruit. You can choose to stop here or go for a third layer. The last layer should be cream with fruit. Add the crystallised rose petals using the cream to keep them in place. You can assemble the pavlova about an hour or two before serving.
Don't worry if the pavlova starts to crack. With the weight of the cream and fruit you will get bits that fall off.and some earthquake like gaps might appear. I think the cracks and slight precariousness of the layers adds to the overall charm.
To make individual meringes spoon out or pipe out dollops of meringue and spread out on a lined greaseproof tray. Flatten slightly to form 2 in circles.