In a medium-sized heatproof bowl, combine egg whites and sugar.
Put the bowl atop a saucepan with about an inch of simmering water. Make sure that the bowl does not reach the water, and vice versa.
Whisk the egg white mixture until all the sugar are dissolved. Test by rubbing a drop between fingers; the mixture should feel smooth and not gritty. The temperature should be hot, but not too hot that you’ll burn your fingers.
Remove the bowl from heat.
[This step is optional and only applicable if you’ll be using a hand mixer, not a stand mixer] Place the bowl in a shallow basin with a little water and a couple of ice cubes. This helps bring down the temperature, especially if like me, you’re living in an infernally hot place.
Whisk the egg white mixture with an electric mixer until volume is about doubled or tripled and looks smooth and glossy. The resulting meringue should form and hold stiff peaks when you lift up the whisk. It should also be down to room temperature by this time.
In a separate bowl, beat/whip the softened butter until fluffy. You can use the same beater attachment, by the way.
Add the meringue to the whipped butter by teaspoonfuls/spatula-fuls, mixing well before each new addition.
Add in the salt, and beat until the frosting is smooth and silky.
Add in the Nutella, one tablespoon at a time. Mix well before each new tablespoonful. Give it a taste before adding more Nutella; you may want more or less of the stuff than what I put in here, depending upon your preference.
Lick the used spatula and beaters clean (or better yet, have your kid do that for you) and congratulate yourself for a yummy frosting well done. ?
This is a small batch recipe, but can be easily doubled or tripled depending on how much frosting you'll need.