Preheat the oven to 400°F (200°C). Spread cubed butternut squash on a baking sheet, drizzle with olive oil, and sprinkle with salt and pepper. Roast for about 25-30 minutes until caramelized and tender.
While the squash roasts, toast the cumin seeds in a dry skillet over medium heat until fragrant, about 1 minute. Then grind them using a mortar and pestle or spice grinder.
Heat olive oil in a large pot over medium heat. Add chopped onion and cook, stirring occasionally, until translucent and soft, about 5 minutes.
Add minced garlic to the onions, cooking for another minute until fragrant. Then stir in the ground cumin, cinnamon, and smoked paprika, cooking for 30 seconds to awaken the spices' aromas.
Add the roasted butternut squash into the pot, breaking it up slightly with the spoon to mingle with the spices and onions.
Pour in the vegetable broth and bring the mixture to a gentle simmer. Cover partially and cook for 10 minutes to allow flavors to meld.
Using an immersion blender or transferring the soup carefully to a blender, puree until smooth and velvety. Return to heat if using a separate blender.
Taste and adjust seasoning with extra salt and pepper as desired. Let the soup heat through for another 2 minutes.
Serve the hot soup garnished with a drizzle of olive oil or a sprinkle of fresh herbs if desired, enjoying its warm, smoky aroma and smooth texture.
