While not a significant toxin, chocolate contains both theobromine and caffeine - neither of which is well-tolerated by parrots when ingested in excess. A small of amount of Nutella, however, is unlikely to be harmful. When it comes to feeding your cockatoo please note the following: Nutritional imbalances are a common cause of illness in our pet birds. Seeds should compose less than 20% of your cockatoo's diet. A diet of mainly seed and nuts has excessive fat, carbohydrates, and phosphorus; marginal protein; adequate vitamin E, and are deficient in amino acids, calcium, available phosphorus, sodium, manganese, zinc, iron, vitamins A, D3 (necessary for efficient absorption of calcium), K, and B12, riboflavin, pantothenic acid, choline, and available niacin. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat. Please respond with further questions or concerns if you wish.