Preheat the oven to 350°F. Put the hazelnuts on a roasting pan and bake in the oven until they smell nutty and the skins crack, about 10-15 minutes. Remove and place in a clean dish towel and rub to remove some of the skins.
Put the hazelnuts into a jar and cover with water. Soak for at least 2 hours or overnight. Strain the nuts. Rinse and put into a blender with 2 cups of fresh water. Blend until smooth and creamy. Strain through a cheesecloth until most of the liquid is removed. Pour the nut milk into a bowl and the maple syrup and salt to taste.