Heat the oil in a large pot over medium heat. Add the onion, salt, and several grinds of fresh pepper and sauté until soft, 5 to 8 minutes. Add the squash and cook until it begins to soften, stirring occasionally, for 8 to 10 minutes.
Add the garlic, sage, rosemary, and ginger. Stir and cook 30 seconds to 1 minute, until fragrant, then add 3 cups of the broth. Bring to a boil, cover, and reduce heat to a simmer. Cook until the squash is tender, 20 to 30 minutes.
Let cool slightly and pour the soup into a blender, working in batches if necessary, and blend until smooth. If your soup is too thick, add up to 1 cup more broth and blend. Season to taste and serve with parsley, pepitas, and crusty bread.