In a large pot or Dutch oven, cook the chopped bacon over medium heat until crispy.
Remove the bacon with a slotted spoon and set aside, leaving the bacon fat in the pot.
Add the chopped onion and celery to the pot with the bacon fat and cook until softened, about 5 minutes.
Stir in the minced garlic and cook for another minute.
Add the diced potatoes, clam juice (or chicken broth), and bay leaf to the pot.
Bring to a boil, then reduce the heat and simmer until the potatoes are tender, about 15-20 minutes.
In a small bowl, whisk together the flour and a small amount of the milk to create a smooth paste.
Stir the flour mixture into the pot and cook for a few minutes until the chowder thickens.
Add the heavy cream, remaining milk, dried thyme, and the juice from the canned clams. Stir to combine.
Add the chopped clams and cook for another 5-10 minutes, until heated through. Do not let the chowder boil.
Season with salt and black pepper to taste.
Remove the bay leaf from the pot.
Ladle the clam chowder into bowls and garnish with the crispy bacon and chopped fresh parsley.
Enjoy your meal!