Whisk the egg whites at medium speed with half the sugar. When they start to form peaks, add the other half of the sugar. Whisk until it is very stiff and forms peaks.
Add the Nutella and gently mix, without combining the two ingredients.
Using a piping bag or spoon, form the cookies on a lined baking tray.
Bake 75 min at 250°F (120°C).
There you are, your Nutella meringue cookies are ready!