Be careful never to let the broth boil after adding clams to any chowder.
Melt butter in soup kettle and Saute cabbage, stirring gently, over low heat until wilted. Add stock, bring to a boil, reduce heat and simmer 25 minutes, partially covered. (Add additional stock or water if necessary.) Add clams and milk to kettle, stir, season with salt and pepper, and heat thoroughly.