Steps
1. Preheat the oven to 350°F (180°C).
2. In a bowl, whisk together eggs and sugar until well combined.
3. Heat water in a saucepan until it's warm but not boiling, then slowly pour it into the egg mixture while continuously whisking.
4. Add Nutella to the mixture and stir until smooth.
5. Pour the mixture into ramekins and place them in a baking dish. Fill the dish with hot water halfway up the sides of the ramekins.
6. Bake for about 30 minutes until the custard is set.
7. Remove from the oven, let it cool, and refrigerate before serving.