Roast the Butternut Squash: Preheat the oven to 400°F (200°C). Spread the cubed butternut squash on a baking sheet, drizzle with 1 tablespoon of olive oil, and season with salt and pepper. Roast for 25-30 minutes, or until tender and lightly caramelized.
Sauté Aromatics: In a large pot, heat the remaining tablespoon of olive oil over medium heat. Add the onion, garlic, and ginger, and sauté for 3-4 minutes, until softened and fragrant.
Combine Ingredients: Add the roasted butternut squash to the pot along with the vegetable broth. Bring to a boil, then reduce heat and simmer for 10 minutes.
Blend the Soup: Using an immersion blender, blend the soup until smooth. Alternatively, transfer the soup in batches to a countertop blender and blend until creamy.
Add the Miso: In a small bowl, mix the miso paste with a bit of hot water to create a smooth liquid. Stir the miso mixture and coconut milk (if using) into the soup, ensuring the soup doesn’t boil, which can affect the flavor of the miso.
Serve: Ladle the soup into bowls and garnish with sliced green onions and sesame seeds. Enjoy hot.