In a small bowl, mix 2 Tablespoons of boiling water and 2 ½ Teaspoons of gelatine powder until the gelatine is dissolved.
In a saucepan, combine 800ml of whipping cream and 500g of Nutella. Heat over low-medium heat, stirring, until the Nutella and cream are melted and smooth.
Add the dissolved gelatine mixture to the Nutella-cream mixture and stir until well combined.
Pour the mixture into serving glasses and refrigerate for about 6 hours until set.
Top with whipped cream and a dusting of cocoa powder before serving.
