Go ahead and use full-fat half-and-half. Our tasting table tried this with fat-free half-and-half and agreed that is doesn't compare to the real thing.
Sauté onion and garlic in hot oil in a Dutch oven over medium-high heat 2 to 3 minutes or until tender. Add squash and next 3 ingredients, and cook 1 minute; stir in broth and chiles. Cover and bring to a boil. Reduce heat to low, and simmer 20 to 25 minutes or until squash is fork-tender.
Remove from heat, and stir in tortilla pieces. Let cool 15 minutes. Process mixture, in batches, in a blender or food processor until smooth, stopping to scrape down sides as needed. Return squash mixture to Dutch oven.
Stir in half-and-half, and cook over medium heat 2 to 3 minutes or until thoroughly heated. Garnish, if desired.
Note: Soup may also be processed with a hand-held blender directly in Dutch oven. We tested with Terra Stix for thinly sliced root vegetable chips.
Note: Nutritional analysis does not include garnish.