If using fresh clams, in a pot, combine the clams and 2 cups of water. Cover, bring to a boil over medium-high heat and cook for 5 minutes. Uncover and continue to cook until the clams open, 5 to 10 minutes (discard any clams that do not open). Transfer the opened clams to a bowl and set aside. Reserve liquid. Clean pot.

Pour reserved liquid plus enough water to make 3 cups total back into the pot through a sieve. Add the potatoes, cover and simmer until tender, about 15 minutes. Remove one-third of the potatoes and set aside. Cook remaining potatoes, covered, until soft, about 10 minutes. Transfer cooked potatoes and liquid to a blender and purée until smooth. Return the soup to the pot.

Lightly coat a skillet with nonstick cooking spray and heat over medium-high heat. Add the onion and celery and cook until soft, about 5 minutes. Add the garlic, thyme, bay leaves and half of the chopped bacon and stir. Sprinkle the flour over the bacon mixture and cook, stirring, about 3 minutes. Add the bacon mixture and reserved potatoes to the soup. Cover and cook on low heat, until heated through, about 5 minutes.

Meanwhile, remove the clams from their shells and roughly chop. Stir the clam meat (either fresh chopped clams or canned chopped clams), half-and-half and sherry into the soup; remove from the heat, cover and set aside, 20 to 30 minutes.

Discard the bay leaves. Season the soup with salt and black pepper to taste and reheat. Serve topped with parsley, chives, dill, paprika and the remaining half of the chopped bacon.