Preheat oven to 350F. Line a baking sheet with parchment paper and set aside. 

In the bowl of a standing mixer fitted with the whisk attachment or a handheld mixer, beat egg whites until soft peaks form (about 5 minutes). Add half of the sugar and beat for 30 seconds. Add remaining sugar and beat on high speed until stiff glossy peaks form (about 2 more minutes). Add vanilla extract and beat for one more minute. Use a rubber spatula to fold in the corn starch and cream of tartar. 

Transfer to a piping bag fitted with desired attachment and pipe onto the prepared baking sheet (make a circle then circle around the sides a couple of times to make a nest). Place in the preheated oven, and turn the temperature down to 200F. Bake for about 45 minutes, until the pavlova is firm and dry. Turn the oven off, but keep the pavlova inside of it to cool.

Meanwhile, make the ganache. Place chocolate chips in a heat-proof bowl at set aside.  

Heat heavy whipping cream in a small sauce pan over medium heat. When it starts to boil, our over the chocolate chips and let sit for 5 minutes. 

Stir the chocolate mixture until smooth. Set aside to cool. 

Chill the metal bowl and whisk attachment for a standing mixer in the freezer for 5 – 15 minutes. 

Remove and add heavy whipping cream, sugar and vanilla. Whip on medium-high speed until stiff peaks form.

Use a rubber spatula to gently fold in the Nutella. I don't like to mix it completely because I like the marbled look. Use a piping bag or spoon to fill the pavlovas. Drizzle with cooled ganache (it helps to use a piping bag). Enjoy immediately.