PLACE avocados and onion in food processor or blender; cover. Process until onion is coarsely chopped.
COMBINE broth and half-and-half in large saucepan. Bring to a boil over medium-high heat; reduce heat to low. Stir in avocado mixture, chiles, cumin, garlic salt and white pepper. Cook, stirring occasionally, for 2 to 3 minutes or until warm. Ladle into bowls. Garnish as desired.