Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper. Place the cubed butternut squash on the sheet, drizzle with olive oil, and toss to coat evenly.
Roast the squash in the oven for about 25-30 minutes, or until it's tender and lightly caramelized in spots. The edges should be golden and fragrant.
While the squash roasts, heat a tablespoon of olive oil in a large pot over medium heat. Add the diced onion and cook, stirring occasionally, until it's translucent and soft, about 5 minutes.
Add the minced garlic to the onion and cook for another minute until fragrant. Be careful not to let the garlic burn.
Transfer the roasted squash into the pot, then pour in the vegetable broth. Bring the mixture to a gentle simmer, allowing the flavors to meld for about 10 minutes.
Use an immersion blender or transfer the soup carefully to a high-speed blender. Blend until smooth and creamy, about 1-2 minutes, stopping to scrape down the sides as needed.
Stir in the coconut milk to add richness, then season with salt and pepper to taste. Blend again briefly to combine everything well.
Taste the soup and adjust seasoning if necessary—add more salt, pepper, or a squeeze of lemon if you like a bright contrast.
Pour the hot soup into bowls and garnish with a drizzle of olive oil, a sprinkle of herbs, or toasted bread on the side for an inviting presentation.
