To toast the hazelnuts, bake in a 375° oven until golden under skins (break one to test), 10 to 15 minutes. When cool enough to handle, rub in a kitchen towel to remove as many skins as possible.
In a food processor, whirl hazelnuts until smooth. Add garbanzos, olive oil, garlic, parsley, and lemon juice, and whirl again until smooth. Add water, 1 tablespoon at a time, to thin to desired consistency. Add salt and pepper to taste. Drizzle with hazelnut oil, if desired.
Note: Nutritional analysis is per tablespoon.