Place a large saucepan over medium heat. Add chopped bacon and cook until the fat is rendered and the pieces are golden and crisp. Use a slotted spoon to transfer the bacon to a paper towel, leaving the fat in the pan for added flavour.
To the same pan, add butter, chopped onion, and celery. Cook over low heat for about 5 minutes, stirring occasionally until softened. Add garlic and sauté for another minute to release its aroma.
Stir in the diced potatoes and cook for 2 minutes, letting them absorb the flavours. This step helps build the chowder’s hearty texture.
Sprinkle the flour over the vegetables. Stir constantly for 1 to 2 minutes to form a light roux. This thickens the chowder without lumps and keeps it silky smooth.
Gradually add the clam juice while stirring. Bring the mixture to a gentle simmer and let it cook uncovered for 10 minutes or until the potatoes are just tender. Avoid boiling, which can break down the starch too quickly.
Add the milk and double cream, stirring to combine. Lower the heat and simmer gently for another 5 minutes. The soup should now begin to look velvety and rich.
Stir in the chopped clams along with their juice. Cook for 2 to 3 minutes more until heated through. Do not overcook the clams as they can become rubbery.
Add salt and a few turns of black pepper. Taste and adjust as needed. Clams and bacon can be salty, so season mindfully.
Sprinkle most of the cooked bacon back into the chowder and stir. Save a few pieces for garnishing when serving.
Ladle the hot chowder into bowls. Garnish with fresh parsley and the reserved bacon. Serve with oyster crackers or slices of warm crusty bread on the side. For an extra touch, drizzle a bit of melted butter on top.