Remove any skin and bones from halibut; cut into bite-sized pieces.
Saute vegetables in 3 Tbsp butter.
Add halibut, chicken broth, salt, and pepper.
Simmer, covered for 5 minutes.
Add milk and heat gently.
Combine remaining 3 Tbsp butter with flour and add to chowder.
Cook and stir chowder until slightly thickened.
Add cheese; cook and stir over low heat until cheese melts.
Sprinkle halibut chowder with parsley.
Makes 6 to 8 servings.