Step by step

Separate the egg yolks from the whites and beat the yolks with the sugar until frothy

Tips
To soften the Nutella, and make it easier to spread, you could try putting it into the microwave for a few seconds, or you can melt it in a bain marie - but the water must never boil.
Trivia
Nutella is mentioned in song lyrics: Negrita, in their album XXX, mention it in a song "Sex" where they sing: "try the recipes, try some cooking, use Nutella, use flour."