6 lb. littleneck clams, rinsed well
6 oz. pancetta, diced
3 Tbs. unsalted butter
1 yellow onion, diced
2 celery stalks, diced
2 garlic cloves, minced
2 tsp. chopped fresh thyme
2 Tbs. all-purpose flour
2 lb. Yukon Gold potatoes, peeled and diced
2 bay leaves
1 cup heavy cream
2 tsp. Worcestershire sauce
Salt and freshly ground black pepper, to taste
Pinch of cayenne pepper
1 Tbs. chopped fresh chives (optional)
Working with 1 clam at a time, hold it over a bowl to catch the juices. Place the blade of a clam knife horizontally across the shell and squeeze to open. Using the tip of the knife, remove the clam meat by cutting it away from the shell; place the meat in a separate bowl. Strain the juices through a fine-mesh sieve lined with cheesecloth into a bowl. Add enough water to the juices to total 5 cups. Coarsely chop the clam meat. Set aside.
In a Dutch oven over medium heat, sauté the pancetta until crisp, about 5 minutes. Pour off all but 1 Tbs. of the fat, then melt the butter in the pan. Add the onion, celery, garlic and thyme and cook, stirring occasionally, until the onion is soft, 3 to 5 minutes. Add the flour and cook for 1 minute more. Add the potatoes, bay leaves and clam juice-water mixture and bring to a boil. Reduce the heat and simmer until the potatoes are tender, about 15 minutes.
Stir in the cream, Worcestershire, salt, black pepper and cayenne. Using a fork, lightly mash the potatoes against the side of the pot to thicken the soup. Add the clams and cook for 2 minutes. Remove the bay leaves and discard. Ladle the soup into warmed bowls and garnish with the chives. Serves 8.