Roast the hazelnuts: Preheat your oven to 180°C (350°F). Spread the hazelnuts on a baking tray lined with parchment paper or a silicone mat. Roast for 10–15 minutes until fragrant and lightly golden.If your hazelnuts still have skins, rub them with a clean kitchen towel after roasting to remove most of the skins. Let them cool slightly. Blend into hazelnut butter: Place the cooled hazelnuts in a food processor or high-speed blender. Blend until they first become crumbly, then continue blending until a smooth, creamy hazelnut butter forms.Pause occasionally to scrape down the sides. Add flavourings: Add the vanilla extract, salt, powdered sugar, cocoa powder, and oil. Blend again until fully combined and smooth.
Add melted chocolate: Pour in the melted, cooled dark chocolate. Process until the mixture becomes glossy, silky, and completely smooth.
Store and enjoy: Transfer the Nutella into a clean jar. Let it cool completely, then seal and store at room temperature or in the fridge.