Preheat the oven to 250°F and line a baking sheet with parchment paper or a silicone mat.
Using a handheld or stand mixer, whip the egg whites on medium-high speed. Add the granulated sugar gradually and then allow the mixture to whip until stiff peaks form.
Transfer the mixture to a piping bag and pipe 4” circles on the lined baking sheet, making sure that it is thick enough to support the toppings once cooked.
Bake for 90 minutes, or until they are firm and dry but not brown. Turn off the oven and leave the pavlovas to cool inside, about 1-2 hours.
For the Fillings
In a small frying pan over medium heat, toast the hazelnuts for 2-3 minutes, stirring often. They should start to smell fragrant but make sure not to let them burn!
Remove from heat and allow to cool completely. Then roughly chop them. Set the chopped nuts aside until ready to use.
Once the hazelnuts are cool, beat the heavy cream with a handheld or stand mixer on medium speed until light and fluffy. Add ½ cup of Nutella and mix just until combined.
Heat the remaining ½ cup of Nutella in a small bowl in the microwave until smooth and pourable.
Coat the top of the pavlova with the Nutella-flavored whipped cream. Next, add the melted Nutella and chopped hazelnuts.
Finish the pavlova with shaved chocolate on top and serve immediately.