Spread the hazelnuts in a single layer on a rimmed baking sheet. Toast the hazelnuts until they're slightly browned and the skin is slightly blistered, about 10 to 15 minutes. Wrap the hazelnuts in a kitchen towel and rub vigorously to remove as much loose skin as possible (some skin may not remove, that's fine). Let cool completely.
Place the chocolate in a microwave-safe bowl and microwave in 30-second bursts, stirring between each burst, until the chocolate is melted and smooth. Let cool completely.
In a food processor, fitted with the knife blade, grind the hazelnuts until they form a paste. Add the oil, sugar, cocoa powder and salt and continue to process until the mixture is as smooth as possible. Add the melted chocolate and blend until smooth. Allow the mixture to cool (will be warm from blending or processing). Store the mixture in an airtight container at room temperature for up to 2 weeks, or refrigerate for up to 4 weeks.
Recipe by Between Carpools at https://betweencarpools.com/spread-some-homemade-nutella-on-your-matzah/