Great recipe from Hugh's Fish Fight on LifeStyle Channel.
Heat a heavy-based pan over a medium heat and add the oil and a knob of butter. When the butter is foaming, add the bacon and sauté until it starts to release some of its fat.
Add the leek, onion and garlic, then cover and sweat gently for around 5 minutes, without letting the vegetables colour.
Add the potato and sweat for 5 minutes more, then pour in the stock and bring to a gentle simmer. Cook, covered, for about 10 minutes, until the potato is soft but not disintegrating.
Meanwhile, scrub the cockles under cold water, discarding any that are damaged or open.
Put a large, wide pan over a high heat and add the wine, a glass of water and a knob of butter. Bring to the boil.
Add the cockles to the boiling, winey liquid. Cover at once with the lid, stir after a minute or so and cover again. Cook for 2-4 minutes, until the cockles are open (discard any that remain firmly closed).
Tip the contents of the pan into a colander, set over a bowl to catch the juices. Set aside a few cockles and pick the remainder from their shells.
Strain the cockle juices through a fine sieve, or a coarse sieve lined with a cotton cloth, and add to the chowder, along with the shelled cockles.
Stir in the cream, season to taste and reheat gently if necessary. Serve piping hot, garnished with the shell-on cockles and accompanied by some bread.