Drain clams in a colander and reserve all the clam juice and set aside.
In a large saucepan over medium heat add ¾ chopped bacon, onion, and celery. Sauté until tender, about 5 minutes. Add in chicken stock and clam juice and simmer 5 minutes.
Add in cubed potatoes and keep simmering until potatoes are tender, but not mushy, about 5 minutes. Season with garlic salt, dried parsley, black pepper, and onion powder. Pour in corn and chopped clams. Bring to a rolling boil.
Whisk half and half and cornstarch or flour together to make a rue and pour into soup. Mix to combine and begins to thicken.
Remove from heat and cook remaining bacon. Garnish with bacon and fresh chopped parsley.
To make the chowder thicker add more cornstarch to the half and half.