Preheat the oven to 180C | Gas mark 4. Place the hazelnuts on a baking sheet in a single layer and roast for 12-15 minutes. This will warm the natural oils and loosen the skins.
Once golden, remove from oven and let them cool slightly. Using your hands, roll the hazelnuts around and to remove most of the skins (they are very bitter so remove as many as you can).
Add the hazelnuts to a food processor and blend until a butter is formed. If your food processor hasn't got enough power, you may have to scrape down sides, blend and repeat a few times.
Heat the chocolate over a double boiler or in the microwave in 30-second increments. Once melted, add the coconut oil and stir until melted.
Once the hazelnut mixture is starting to look smooth, add the milk and blend for around 30 seconds. Slowly add in the melted chocolate, 2 tablespoons at a time, blending in between.
Taste and adjust seasonings as needed. Transfer to a jar and store at room temperature.