Makes about 1 1/2 cups (375 mL).
Preheat the oven to 350ºF (180ºC). Place the hazelnut in a single layer in a baking dish and toast for about 15 minutes, until the skins darken and start to crack. Allow the hazelnuts to cool then either rub them in a tea towel to remove the skins, or put them in a colander and swirl them around (the skins will come off and fall through the holes of the colander).
Place the peeled hazelnuts in bowl of a food processor along with the icing sugar, oil, chocolate, vanilla and salt. Pulse this until the mixture becomes a smooth paste – the chocolate will melt from the friction of the spinning blade, making the paste fluid, but once it sets up to room temperature, it will be a spreadable consistency. If the paste doesn’t set within 2 hours, it can be chilled to set, but then stored at room temperature to be spreadable.
The chocolate hazelnut spread will keep in an airtight container at room temperature for a month.