01 - Set your oven to 400°F to prepare for roasting the vegetables.
02 - In a large bowl, toss the cubed butternut squash, chopped onion, sliced carrots, and garlic cloves with olive oil, ground cumin, cinnamon, salt, and pepper until evenly coated.
03 - Spread the seasoned vegetables in a single layer on a baking sheet. Roast for 30 to 35 minutes, stirring halfway through, until the squash is golden and tender.
04 - Transfer the roasted vegetables to a large pot. Pour in the vegetable broth and bring to a boil over medium-high heat, then reduce to low and simmer for 10 minutes to allow flavors to meld.
05 - Use an immersion blender directly in the pot to puree the soup until completely smooth and creamy. Alternatively, blend in batches using a countertop blender, being cautious with hot liquids.
06 - Stir in the coconut milk or heavy cream if using. Taste the soup and adjust salt and pepper as needed.
07 - Ladle the hot soup into bowls and garnish with fresh thyme leaves, toasted pumpkin seeds, and an optional swirl of cream or coconut milk.