In a large Dutch oven, cook bacon over medium heat until crispy, about 8-10 minutes. Remove and set aside.

Add butter to the bacon drippings, then add celery, leek, and onion. Sauté for 5-7 minutes until tender. Stir in garlic and cook for 1 additional minute.

Stir in potatoes, broth, and clam juice. Season with salt, pepper, and thyme. Bring to a boil, then simmer uncovered for 15-20 minutes until potatoes are fork-tender.

Mix flour with half-and-half until smooth. Gradually stir into the chowder and cook for 1-2 minutes.

Add clams, bay shrimp, and crab meat. Pour in remaining half-and-half, gently heating through without boiling.

Crumble bacon back into the chowder with bay leaves and Old Bay seasoning. Stir and heat for 2-3 minutes. Remove bay leaves before serving.

Garnish each bowl with additional crumbled bacon and chopped chives or green onions before serving.