When I adopted my first parrot two years ago, her foster mom gave me a container of Lafeber Nutriberries. She had purchased them for her bird and it turned out that he didn't like them. She told me that Lafeber products are excellent and that these Nutriberries could be fed as the main diet rather than just an occasional treat. I've sinced learned that her advice was not the best but I do still continue to purchase this product as an occasional treat.
Nutriberries are round, solid balls of corn, seed, nuts, egg, oats, etc. They come in different sizes for parakeets, cockatiels, parrots,...