Macadamia nuts are newcomers to the world’s table. They come from two evergreen tropical trees (Macadamia tetraphylla and M. integrifolia) native to northeastern Australia, where the aborigines enjoyed them for thousands of years before they were noticed and named by Europeans (for John Macadam, a Scots-born chemist, in 1858). Macadamias were introduced to Hawaii in the 1890s, and became commercially significant there around 1930. Today Australia and Hawaii are the main producers, but their output remains relatively small, and macadamias are therefore among the most expensive nuts. Because their shells are extremely hard, they are sold almost exclusively out-of-shell, often packed in cans or bottles to protect them from air and rancidity. Macadamias have the highest fat content of the tree nuts, and it’s mostly monounsaturated (65% oleic acid). Their flavor is mild and delicate.