The quality of creaminess does not belong to cream alone; onions have it too. The creaminess of cooked-down onions acquires a piquant sweetness that in this recipe envelops the fricasseed chicken. To make onions clingingly creamy and tasty, it is worth repeating here what has been said elsewhere: They must first be cooked in a covered pan a long time over low heat, then uncovered and browned lightly.