Place the peeled hazelnuts on a baking sheet and roast in the oven for 15 minutes at 350 degrees. Briefly cool then run the hazelnuts in the food processor on high speed for 2-3 minutes until very finely chopped, stopping to scrape down as needed. Add the cocoa powder, maple syrup, oil, salt and vanilla and run for another minute. Pour in the milk and pulse until smooth. Add more milk if needed. Taste and adjust the maple, vanilla and salt as you like.