Preheat oven to 180 C / Gas 4. Line a round cake tin with baking parchment and set aside.
Crack eggs into a mixing bowl and beat on high speed until the mixture triples in volume. This took me around 5 minutes.
Spoon nutella® into a medium microwave-safe bowl and microwave for 15 to 20 seconds until soft.
Spoon one third of the egg mixture and fold using a metal spoon to mix in nutella® until entirely combined. Continue with another third of egg mixture and then again until all the egg and nutella® is combined. Spoon the mixture into the cake tin.
Bake in the preheated oven for 25 to 30 minutes or until a skewer inserted into the centre comes out clean. Remove from the oven and allow the cake to cool in the tin. Slice and serve.