This roasted acorn squash soup makes a creamy soup that's fortified with onions, carrots, butter, half-and-half, and warm spices that scream fall.
Preheat the oven to 400 degrees F (200 degrees C).
Arrange squash, cut-side down, in a baking dish; add enough water to cover bottom of the dish.
Bake squash in the preheated oven until easily pierced with a fork, about 45 minutes. Remove from the oven; cool until easily handled. Scoop flesh into a bowl and set aside.
Melt butter in a large pot over medium-high heat. Add onion, carrot, and garlic; stir until onions soften, 5 to 7 minutes. Add stock and squash; simmer for 20 minutes.
Transfer mixture to a blender in batches and purée until smooth. Return to pot.
Stir in half-and-half, nutmeg, and cinnamon; season with salt and pepper. Thin the soup with water, if desired.