Note This is my trial-and-error adaptation of the "official" cassoulet recipe published by the Grande Confrérie du Cassoulet de Castelnaudary. The finished dish should be moist but not at all runny. If you don't own a cassole, use a four-litre cast-iron casserole. You'll need to begin this recipe 2 days ahead. Duck confit is available from select delicatessens and French food shops. Alternatively, you can make your own - see our masterclass on duck confit. Remaining duck fat will keep refrigerated for 1 month.