Preheat the oven to 400 degrees F.

To make the pavlova, begin by beating egg whites and salt until soft peaks form. Gradually add sugar and cornstarch until the mixture reaches stiff peaks.

Place spoonfuls of the meringue onto a baking tray lined with parchment paper or a silicone baking mat. Reduce temperature to 250 degrees and cook for 1 hour. Turn the oven off and allow pavlova to cool in the oven.

While the pavlova is baking, combine ingredients for the mixed berry sauce in a medium saucepan over medium-high heat. Allow the mixture to start bubbling, then reduce to a simmer while smashing up the berries with the back of a wooden spoon. Cook for approximately 15 minutes until thickened and jam-like in consistency. Cool completely in the refrigerator until ready to serve.

Place the pavlova on a large serving plate or marble slab, and crush slightly with the back of a large spoon. Spoon over the whipped cream, then drizzle with the mixed berry sauce.