- Preheat oven to 375 degrees F. Combine all ingredients except milk and parsley in 4-quart ovenproof casserole. Cover and bake until fish flakes into pieces and potatoes are tender, about 1 hour.
- Transfer casserole to stovetop. Slowly stir in milk. Simmer gently over low heat until rewarmed, about 5 minutes. Add parsley. Serve immediately.