Preheat oven to 425ºF.
Put squash cubes, onion, and garlic cloves on a large rimmed baking sheet. Sprinkle with salt, pepper and drizzle oil over top. Use your hands to toss everything around so it’s easily coated.
Roast for 35–40 minutes on a lower oven rack, tossing things around with a spatula a couple of times during cooking.
Transfer roasted items to a medium to large soup pot. Add chicken broth and heat to a simmer. Let it simmer for about 5 minutes and then blend it with an immersion blender (or in batches with a countertop blender) until smooth.
Stir in coconut milk or cream. Add a little more salt, if needed, before serving.
Indian-spiced: Stir in ½ teaspoon of garam masala and add the juice from a lime at the end.
Chipotle-Lime: Stir in ¼ teaspoon of dried chipotle powder (or ½ chipotle pepper from a can of chipotles in adobo sauce) and ½ teaspoon ground cumin when you add the chicken broth. Replace the coconut milk with an extra cup or so of chicken broth, and add the juice from 1 lime at the end.
Apple Bacon: Omit the garlic cloves and add 1 large sliced tart apple to the roasting pan. Replace the coconut milk with an extra cup or so of chicken broth. Add 1 to 2 tablespoons (to taste) of apple cider vinegar at the end. Garnish with some crispy bacon crumbles.