In large pan, saute garlic in butter until tender. Stir in pepper and cook a few minutes longer. Add squash and broth, cover, and simmer until squash is tender. Pour into blender (no more than two-thirds full), add dill and parsley, and puree the mixture in batches. Pour into freezer-safe containers and let cool slightly. Cover containers, label, and freeze.
To serve: Reheat gently, thinning with a little cream or milk if necessary. Season with salt and pepper; garnish with grated Parmesan cheese.