Cut squash in half. Scoop out seeds and discard. Sprinkle with olive oil. Lay face down on a baking sheet. Bake for 40-50 minutes or until tender. Remove from oven. Let cool.
Scoop out pulp. Discard skin. Chop into pieces.
Using a large pot, melt butter over medium-low heat. Add onion and saute until translucent.
Add roasted squash and chicken broth.
Pour into a blender and blend until smooth or use an immersion blender.
Season with salt and pepper to taste.
Notes
For creaminess, feel free to add a splash of milk, half and half or heavy cream. But I find it to taste amazing as is.