Heat the olive oil and butter in a large pot over medium heat. Once the butter melts, add the onion, celery, and carrots. Sauté for 5 to 7 minutes until softened but not browned. Stir in the garlic and cook for another minute.

Sprinkle in the thyme, red pepper flakes if using, and a pinch of salt. Stir to coat the vegetables evenly. This step builds the aromatic foundation of the chowder.

Add the diced potatoes to the pot and stir to combine. Cook for 2 to 3 minutes, allowing the potatoes to absorb some of the flavour before adding liquid.

Add the reserved clam juice, bottled clam juice, and chopped tomatoes with their juices. Stir well and bring the mixture to a gentle boil.

Reduce the heat to low, add the bay leaf, and cover. Simmer for 20 to 25 minutes until the potatoes are tender but not falling apart. Stir occasionally to prevent sticking.

Stir in the chopped clams and their juices. Simmer uncovered for 5 to 7 minutes. Avoid overcooking the clams, as they can become rubbery.

Taste the broth and adjust with salt and black pepper as needed. If the tomatoes are particularly acidic, a pinch of sugar can help balance the flavour.

Remove the bay leaf and stir in the chopped parsley. This adds a fresh, herbal note that lifts the entire dish.

Let the chowder sit off the heat for 5 minutes. This allows the flavours to meld and the texture to settle slightly before ladling.

Serve hot with crusty bread or oyster crackers. A drizzle of olive oil or a squeeze of lemon can enhance the brightness. Garnish with extra parsley if desired.