In a heavy stockpot or Dutch oven, melt the butter and then add the onion and cook, stirring occasionally, until the onion is translucent about 5-7 minutes.
Meanwhile, drain the clam juice from the chopped clams and combine with enough bottled juice to equal 3 cups of liquid.
Once the onions are cooked, add the flour and cook over low heat for 2-3 minutes, to form the roux. The roux should remain golden and not be browned.
Now, whisk in the clam juice, bring to a boil, and cook for 5 minutes, stirring occasionally. The liquid should be the consistency of heavy cream. If it is too thick, add more clam juice (or water) to adjust the consistency.
Add the potatoes and simmer until tender, about 10-15 minutes.
When the potatoes are tender, add the clams and cream to the soup base. Simmer for 1-2 minutes. Remove from heat before boiling so the milk doesn't separate.
Season to taste with salt and pepper. Garnish with Oyster Crackers and freshly chopped parsley.
Serving Suggestions: Serve with our New England Clam Cakes.