1. Preheat the oven to 200°C (400°F).
2. Separate the egg whites from the yolks, then beat the egg whites until they become frothy.
3. Add the sugar and continue beating until you obtain a meringue-like mixture.
4. Add the egg yolks and beat for a few more moments.
5. Gently fold in the Cornstarch using a spatula.
6. Spread the batter on a baking sheet lined with parchment paper, to a thickness of about 1 cm.
7. Place the baking sheet in the oven at 200°C (400°F) for 6 to 8 minutes.
8. Let it cool.
9. Spread Nutella on top.
10. Roll the cake with the Nutella inside.
11. Cover with more Nutella.