Preheat oven to 180°C (350°F). Spread hazelnuts on a baking tray and roast for 10–12 minutes, until fragrant and skins crack.
Once cooled slightly, rub hazelnuts in a clean kitchen towel to remove most of the skins. A few bits left on are fine.
Add hazelnuts to a food processor or high-speed blender. Blend until smooth, scraping down the sides as needed. This may take 5–10 minutes.
Add cacao, maple syrup , vanilla, salt, and a little water. Blend until silky and spreadable.
Add more cacao for a richer chocolate flavor, more maple for sweetness , or liquid for smoother texture.
