In a large saucepan over medium high heat, fry the bacon until crisp, about 10 minutes. Drain on paper towels, reserving the bacon fat in the pan. Crumble the bacon and set aside.
In the same saucepan with the bacon fat, saute the onion and potatoes for 3 to 5 minutes. Sprinkle with the flour and stir well to coat (making a roux).
Pour in the clam juice, bring to a boil, reduce heat to low and simmer for about 15 minutes, or until potatoes are tender.
Add the half-and-half and minced clams and season with salt and pepper to taste. Finally, whisk in the heavy cream, if desired. Allow to heat through, about 5 minutes. Garnish with the parsley and crumbled bacon. (Note: Do not boil if adding cream.)