Preheat oven to 300 degrees. Roast hazelnuts for 9-11 minutes, shaking the pan once or twice during roasting, or until fragrant.
Once cool, whiz nuts in the food processor, stopping occasionally to scrape down the sides. (For me this took about 7 minutes. Mine never got quite to the nut butter stage, but rather tiny pulverized crumbs of nuts.)
Put olive oil and chocolate in a small bowl and microwave 15 seconds at a time until melted, stirring in between, for about a minute altogether. Add this to hazelnuts and pulse a couple of times.
Add remaining ingredients (hazelnut milk through salt) and pulse until incorporated and spreadable.
Spread and scoop to your heart's delight. Store in the refrigerator.