Preheat the oven to 400°F (200°C). Place the peeled and cubed butternut squash on a baking sheet, drizzle with olive oil, and toss to coat.
Roast the squash in the oven for about 25-30 minutes, until it becomes tender and begins to caramelize around the edges, filling your kitchen with sweet, nutty aromas.
While the squash roasts, heat a large pot over medium heat and add a splash of oil. Sauté the diced onion until translucent and fragrant, about 5 minutes.
Add the minced ginger to the onions and cook for another minute until it releases a spicy, aromatic scent.
Once the squash is roasted and has cooled slightly, add it to the pot with the sautéed onion and ginger.
Pour in the vegetable broth and bring the mixture to a gentle simmer, allowing the flavors to meld for about 10 minutes.
Use an immersion blender to carefully blend the soup directly in the pot until smooth and creamy, or transfer to a blender in batches and puree.
Taste the soup and season with salt and pepper as needed, blending again briefly if necessary to incorporate.
Reheat gently if needed and serve hot, garnished with a drizzle of olive oil or a dollop of sour cream if desired.
