Brussels sprouts (Brassica oleracea var. gemmifera) are a cabbage cultivar grown not for one big head but for the dozens of small, dense leafy buds that grow in a spiral up a tall, thick stalk — in effect a column of miniature cabbages. They are sulfurous, nutty and faintly bitter, sweeten after frost, and turn caramelised and savoury when roasted, the cooking method that rescued them from a long reputation as the most hated vegetable on the plate.