In a large heavy pot or Dutch oven over medium heat, melt 2 tablespoons butter. Add 3 tablespoons flour and whisk constantly for 2 minutes until the mixture is pale golden and bubbles lightly (cook off raw flour taste).

Slowly whisk in 1 cup milk until smooth, then add 4 cups fish stock or clam juice while whisking to avoid lumps. Bring to a gentle simmer.

Reduce heat to low and stir in 1 cup heavy cream. Keep the base at a gentle simmer (do not boil vigorously to prevent dairy separation).

Vegetables & Aromatics

If using bacon or salt pork, in a separate skillet over medium heat, render the diced bacon until crisp, about 6–8 minutes. Transfer cooked bacon to a paper towel-lined plate and reserve 1 tablespoon fat; discard excess. If not using bacon, melt 1 tablespoon butter in the pot after the roux step.

Add the diced onion, celery, and carrot to the pot with the roux-based liquid (or to the reserved bacon fat/butter). Sauté over medium heat until the vegetables are softened and translucent, about 6–8 minutes.

Add the diced potatoes, 1 teaspoon salt, 1/2 teaspoon black pepper, 1 tablespoon fresh thyme leaves (or 1/2 teaspoon dried thyme), and 1 bay leaf. Stir to combine.

Bring the chowder to a gentle simmer and cook until potatoes are tender, about 12–15 minutes. Stir occasionally to prevent sticking.

Fish & Finishing

When potatoes are nearly tender, taste the broth and adjust seasoning with additional salt and pepper if needed. Remove and discard the bay leaf.

Gently add the 1 pound of fish pieces into the simmering chowder. Simmer gently until the fish is opaque and flakes easily, 4–6 minutes depending on piece size. Do not stir vigorously to keep fish pieces intact.

Stir in the cooked bacon (if used), 2 tablespoons chopped parsley, 1 tablespoon chives (if using), and 1 teaspoon lemon juice to brighten flavors. Warm through for 1 minute, then remove from heat.

Adjust final seasoning and consistency. If chowder is too thick, stir in up to 1/2 cup additional milk or stock until desired texture is reached.

Serve

Ladle chowder into warmed bowls. Garnish with extra chopped parsley, a sprinkle of chives, and freshly ground black pepper to taste. Serve with crackers or crusty bread.