Preheat your oven to 400°F (200°C). Peel the sweet potatoes and carrots, then chop them into roughly 2-3 cm chunks.
Spread the chopped vegetables on a baking sheet, drizzle with olive oil, and toss to coat evenly. Roast in the oven for about 25-30 minutes, until the vegetables are tender and slightly caramelized around the edges.
While the vegetables are roasting, heat a large heavy-bottomed pot over medium heat. Add a splash of olive oil and sauté the minced garlic for about 1 minute, until fragrant and just starting to turn golden.
Add the roasted sweet potatoes and carrots to the pot, then pour in the vegetable broth. Bring the mixture to a gentle boil, then reduce the heat, cover, and simmer for about 10 minutes to allow the flavors to meld.
Once the vegetables are soft, use an immersion blender to puree the soup directly in the pot until completely smooth. If you don’t have an immersion blender, carefully transfer the soup in batches to a blender and blend until silky, then return it to the pot.
Taste the soup and season with salt and pepper as needed. Let it simmer for another 2-3 minutes to meld the flavors.
Serve the soup hot, garnished with a swirl of cream or a sprinkle of fresh herbs if desired. Enjoy the velvety, sweet, and earthy flavors in every spoonful.