Preheat your oven to 400°F (200°C). Spread the cubed butternut squash and sliced carrots on a baking sheet, then drizzle with olive oil and toss to coat evenly.
Roast the vegetables in the oven for about 35-40 minutes, until they are golden around the edges and very tender when pierced with a fork.
While the vegetables roast, heat a little olive oil in a soup pot over medium heat. Add the chopped onion and cook until translucent and fragrant, about 5 minutes.
Add the minced garlic to the onions and sauté for another minute until fragrant, being careful not to burn the garlic.
Once the roasted vegetables are ready, add them to the pot with the onions and garlic.
Pour in the vegetable broth and bring the mixture to a gentle simmer. Let it cook for 10 minutes to allow flavors to meld.
Use an immersion blender or carefully transfer the soup to a blender and blend until completely smooth and creamy.
Return the blended soup to the pot (if using a blender), then season with salt and pepper to taste. Warm through if needed.
Serve the soup hot, garnished with a drizzle of olive oil or fresh herbs if desired.
