Trim the ends off the butternut squash. Stand it upright on a flat cut end to stabilize, then peel with a veggie peeler or knife. Halve lengthwise, scoop out the seeds, and cut into cubes.
In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes, until soft. Add the squash, sage, garlic, ginger, nutmeg, and salt. Cook, stirring occasionally, until aromatic.
Pour in the chicken broth, using just enough to barely cover the vegetables. Bring to a boil, then reduce the heat, cover, and simmer on low for 20 minutes, or until the squash is fork-tender.
Uncover the pot and let the soup cool slightly. Using an immersion blender, blend the soup until completely smooth. Season with salt and pepper to taste, then serve warm with bread or croutons
Notes
If you use the countertop blender, make sure to blend it in batches.
You can store the soup in the fridge for about 3-4 days or freeze it up to 3 months.