Preheat your oven to 200°C (400°F). Toss the chopped butternut squash and sweet potatoes with a tablespoon of olive oil, salt, and pepper. Spread them out on a baking tray and roast for about 25-30 minutes until tender.

In a large pot, heat the remaining tablespoon of olive oil over medium heat. Add the sliced onion and sauté until soft and translucent, about 5 minutes. Add the garlic and cook for another minute.

Add the roasted squash and sweet potatoes to the pot. Stir in the ground cumin, cinnamon, chili powder, and chili flakes. Pour in the stock or water and bring to a simmer.

Once everything is tender, carefully blend the soup until smooth using an immersion blender or transfer to a regular blender in batches. Return to the pot.

Stir in the coconut milk. Taste and adjust the seasoning with salt and pepper as needed. If the soup is too thick, add more stock or water to reach your desired consistency.