Ham and Leek Croquetas

Line a baking tray with baking paper.

Heat the butter in a medium saucepan. Add the leek, garlic and a pinch of salt. Cover and cook for 10 minutes until very soft, stirring often. Add the prosciutto and cook for 1 minute.

Stir in the flour and cook for 1 minute. Stir in half the milk to make a thick paste, then stir in the rest. Season generously and cook over a low heat for 3 minutes, stirring constantly. The mixture will be very thick with a silky sheen and should be pulling away from the sides of the saucepan. Stir in the cheese and nutmeg. Transfer to a shallow dish and press a piece of plastic wrap down onto the surface to prevent a skin forming. Cool then chill for several hours or overnight until very firm.

Put the flour, eggs and breadcrumbs into three separate bowls and season each. With lightly floured hands, roll spoonfuls of the cold leek mixture into 4cm-long cylinders. Roll in flour, then egg, then breadcrumbs, making sure they are well coated. Place on a lined tray and chill for 2½ hours until very firm.

Heat 4cm of oil in a deep sauté pan or wok to 175°C on a kitchen thermometer, or until a piece of bread turns golden in 30 seconds. Cook the croquetas in batches for about 3 minutes, or until golden. Don't cook them too fast or the centres will still be cold. Drain on kitchen towels, then keep warm in a low oven until they are all cooked.