This is my most go to crab bisque recipe. I try to keep a container in the freezer to add all my seafood shells to and when I have enuf, I'll make a stock out of that to use in the bisque instead of the chix stock.
Sauté onion in butter. Add flour; cook and stir 1 minute. Gradually stir in chicken broth and half-and-half; cook and stir 5 minutes. Break crab into chunks; add to broth. Salt to taste. Heat thoroughly. Garnish with parsley.