Spread the hazelnuts on a baking tray and roast them in a preheated oven to 350ºF (180ºC), stirring them halfway through cooking time, for 10 to 15 minutes, until the hazelnuts are golden brown.
Place the chocolate in a microwave-safe bowl and heat for 30 seconds, then stir with a spoon until the chocolate is fully melted and keep the chocolate warm.
Once the hazelnuts are roasted, place them in a clean tea towel and rub them to loosen the skins. Remove as much of the skins as possible then transfer the warm hazelnuts into a food processor or powerful blender.
Add the sugar into the food processor and blend the ingredients until smooth, depending on your food processor it may take 2 to 5 minutes. Blend until you have a smooth paste.
With the motor still running, pour the oil into the food processor, followed by the warm milk and warm chocolate and blend until smooth and fully combined.
Pour the chocolate hazelnut spread in a large sterilized airtight jar and store in the fridge up to one week.
