In a large saucepan, heat butter over medium-high heat. Add onion and sage; cook and stir 2-4 minutes or until tender. Add broth, apples and water; bring to a boil. Reduce heat; simmer, covered, 12 minutes.
Add squash, ginger and salt; return to a boil. Reduce heat; simmer, uncovered, 10 minutes to allow flavors to blend. Remove from heat; cool slightly.
Process in batches in a blender until smooth; return to pan. Add milk; heat through, stirring occasionally (do not allow to boil). Freeze option: Freeze cooled soup in freezer containers. To use, partially thaw in refrigerator overnight. Heat through in a saucepan, stirring occasionally; add broth if necessary.