This is not real New England style clam chowder. I am using canned clams here, and they are not tasty enough on their own to use in a traditional chowder which is mostly clam and potato without a lot of additional ingredients or seasonings.
Using a medium (6 - 8 quart) stockpot, fry bacon until crisp. Reserve bacon for garnish, pour off all the grease, but leave cooked bits and residual bacon grease to sauté the chopped onion, carrots and celery, until they start to soften. Add diced potatoes, corn, clam juice, dried herbs, garlic powder, white pepper and bottled clam juice and juice squeezed from canned clams. Simmer about 20 minutes until potatoes are done, Add instant potato, parsley and mushrooms, Simmer another 10 - 15 minutes to reconstitute the mushrooms*. Add cream. Taste for salt. Serve with crumbled bacon.
Note: I add parsley and clams last in the process because they can overcook. Add more or less cream to taste, and if you use instant mashed potatoes, just add directly to the soup and keep stirring until desired texture is reached. If you thicken with flour and water, use about 1⁄2 cup flour with a cup of water, shake in a covered jar and pour through strainer or you will get lumps.
I’ve made clam chowder a lot, and this is the best ever. I think the mushrooms were just what it needed.
* I recently decided it’s best to reconstitute the dry mushrooms ahead of time to be sure they are tender enough.