Peel, seed, and cube butternut squash. In 6-qt. Dutch oven melt butter over medium-high heat. Add fresh squash (if using frozen squash add with apples and broth), onion, carrot, celery, and garlic. Cook, stirring frequently, 10 minutes or until vegetables are tender. Add apples, broth, cider, and peppers. Bring to boiling; reduce heat. Cover; simmer 25 minutes or until vegetables and apples are tender. Remove from heat; cool slightly.
When slightly cooled, puree in pot using an immersion blender. (Or puree in batches in a blender; return soup to saucepan.) Blend in sour cream. Heat through. Remove from heat; stir in shredded Gouda until melted. Top with bacon, celery leaves, and/or Gouda cheese. Makes 8 servings.