In a large saucepan or dutch oven, add onions, celery and potatoes, and the clam juice - add a bit of water or chicken broth if you have to, to cover them. Heat over medium-high heat - bring to a boil, then reduce heat and simmer while you complete the creamy mixture (next).
In another pot - over medium heat - melt the butter then whisk in the flour until smooth. Let cook for 20 seconds, season with salt and pepper.
Add the half and half to the butter and flour, stirring constantly so there are no lumps.
Add the half and half mixture to the vegetables and broth.
Add the chopped clams, simmer for 10 minutes, until the potatoes are tender.
Sprinkle bacon and extra green onions (scallions) on top.
TO FREEZE - Cool completely, mix in the bacon. Freeze.TO REHEAT - Thaw and heat gently in the microwave or saucepan.