Add the onion, salt, and pepper (to taste) and sauté until soft, about 5-8 minutes.
Add squash and cook until it starts to soften, occasionally stirring, for 8-10 minutes.
Add the garlic, sage, rosemary, and ginger. Stir and cook 30 seconds-1 minute. Add 3 cups of the vegetable broth.
Bring to a boil, cover, and reduce to a simmer. Cook until the squash is tender, which should be about 20-30 minutes.
Let the soup cool slightly and pour the soup into a blender and pulse until smooth. Work in batches if you need to. If the soup is too thick, add up to 1 cup more broth and blend. Season to taste.
Notes
Serve with chopped parsley, toasted pepitas, and crusty bread