Toss butternut squash and onion with garlic and olive oil. Spread in a single layer on a foil-lined baking sheet and season to taste with salt and pepper. Roast in oven for 25 to 30 minutes.
Combine squash and chicken broth in blender and puree on high speed until well blended. Stir in half and half. Serve hot.
Seasoning options:
Sage: Finely chop 6 fresh sage leaves and toss with butternut squash before roasting. Garnish soup with extra chopped fresh sage.
Autumn Spiced: After adding half and half, add cinnamon and nutmeg to taste.