In a mixing bowl whisk the 4 egg whites, if using an electric mixer use medium speed, until they form soft peaks.
Add sugar, a tablespoon at a time, while continuously whisking until egg mixture forms stiff peaks (should be white and glossy)
Sprinkle vinegar and cornstarch over mixture and gently fold in.
Cover a sheet pan with parchment paper and using a rubber spatula gently scrap the meringue onto the parchment paper and form a large circle (11 inch diameter) with the edges slightly higher than the center. Bake for 1 hr and 15 minutes or until it changes to a pale cream color and is dry to touch.
Turn off the oven and allow the meringue to cool inside the oven. It will harden as it cools. The cooled meringue can be stored in an airtight container for a couple of days.
Pumpkin whip cream
In a mixing bowl whip heavy cream with electric mixer until soft peaks form.
Add a tablespoon of sugar to whip cream and whip a few seconds longer.
In another bowl, combine pumpkin puree, maple syrup and 1/4 tsp of cinnamon.
Carefully fold pumpkin mixture into the whip cream until combined.
Mound pumpkin whip cream on top of pavlova.
Place 1/2 tsp of cinnamon and 1/2 tablespoon of powder sugar in a fine mesh sieve and lightly tap the side to dust the cream with the sugar and cinnamon.