Preheat oven to 275 degrees. Line a baking sheet with parchment paper.
Beat the egg whites on high speed until foamy. Gradually add the sugar and continue to beat until stiff, glossy peaks form. Turn off the mixer; add the corn starch, vinegar, and vanilla then beat into the egg whites, scraping the sides of the bowl if necessary. Sift the cocoa powder into the egg whites and fold in with a rubber spatula until the mixture is no longer streaky. Dump the mixture onto the prepared baking sheet and, using the back of a large spoon, push the mixture into a circle about 8 inches in diameter with a well in the center. Bake for 1 hour or until the outside is crispy, turn off the heat and let sit in the oven for another hour. Remove from the oven and let cool completely.
Place the chocolate hazelnut spread in a microwave safe bowl and microwave for about 10 seconds or until it is softened. Whip the cream until soft peaks form. Stir ¼ of the whipped cream into the chocolate hazelnut spread and then fold that mixture gently into the cream.
Place the meringue on a serving plate; fill the well in the center with the whipped cream, garnish with grated chocolate and chopped hazelnuts.