Preheat the oven to 400°F (200°C). Arrange the peeled and chopped butternut squash and sliced carrots on a baking sheet. Drizzle with olive oil and toss to coat evenly.
Roast the vegetables in the oven for about 30-40 minutes, until they are deeply golden and caramelized around the edges. The aroma should start to fill the kitchen with warm, sweet scents.
Remove the roasted vegetables from the oven and let them cool slightly for a few minutes. Then transfer them to your blender or a large pot if using an immersion blender.
Add vegetable broth to the blender, along with ground cumin and cinnamon if using. Blend until smooth and creamy, adjusting the consistency with more broth if needed.
Pour the pureed soup into a pot and gently heat over medium-low heat. Season with salt and pepper to taste, stirring occasionally.
Once the soup is warmed through and seasoned to your liking, ladle it into bowls. The soup should have a glossy, rich appearance with a vibrant orange hue.