Melt margarine in medium saucepan over medium heat. Add onion and cook until onion is tender. When onions are almost done, add garlic and cook 1 to 2 minutes more.
While onions are cooking, in a medium bowl combine half of the olives, the soup, half of the sour cream, and the green chilies. Mix well.
When onions and garlic are done, add sour cream mixture and stir to combine.
Reserve 3/4 cup of the mixture and set aside for the sauce.
Stir chicken and 1/2 cup cheese into remaining filling.