In a large saucepan over medium heat, melt 1 tablespoon butter; add onions, carrots and celery, stirring and cooking until onion is tender. Add fish, potatoes, bay leaf, salt, thyme, pepper, and wine or water. Cover and simmer for 15 to 20 minutes, until fish is cooked. Break fish into chunks. Add milk and remaining 1 tablespoon butter; heat through. Discard bay leaf, sprinkle with parsley and serve.
Fish chowder recipe serves 4.