Cook bacon in a large nonstick pan until crispy. Remove the bacon and discard the bacon grease. (If you like a lot of bacon flavor in your chowder, use the bacon grease to cook the shallot, garlic and celery and omit the butter and oil.)
Add the butter and oil to the pan. Add the shallot, garlic, and celery and cook until the shallots are translucent.
Do not let the vegetables brown. Remove the vegetables from the pan into a small bowl and set aside.
Pour the clam juice into the pan and add the sliced potatoes. Bring the clam juice to a soft rolling boil and cook the potatoes until fork tender. Don't let them get to the point of falling apart.
While the potatoes are cooking, rinse the fresh clams under cold running water to remove any sand. Discard any clams that are already open. Add the fresh clams to the pot with the potatoes and cover with a lid.
Continue cooking until the clams have opened, about 3-4 minutes. If any of the clams do not open discard them. Use tongs to remove the cooked clams from the pot. Set aside.
Add the corn to the pot and cook for one minute. Add the canned clams plus the juice, and the crumbled bacon. Stir to combine and continue cooking over low heat until heated through.
Pour in ¼ cup heavy cream, remove from heat and stir to combine. taste the broth and add salt and pepper to taste.
Pour the soup into a serving bowl and top with the fresh cooked clams in the shell. Garnish with chopped parsley and oyster crackers.