Heat oil or ghee in a large soup pot. Add carrot, celery, and onion. Cook until vegetables have begun to soften and onion turns translucent. Stir in butternut squash, thyme, chicken broth, salt and pepper. Bring to a boil, reduce heat, and simmer until squash is fork-tender. Use an immersion blender to purée soup. Alternatively, let the soup cool slightly and carefully purée in batches in an upright blender.
Garnish with Parsley Pepita Pesto.
Tip: Double the batch and freeze after cooling completely.