Preheat the oven to 190ºC (375ºF).

Peel and cut the butternut squash and sweet potatoes into large chunks (about 2 inches). Slice the onion into half-moons. Place all the vegetables and garlic cloves in a roasting tin and drizzle with olive oil. Sprinkle with cumin, cinnamon, chilli powder, salt, and pepper.

Roast the vegetables in the oven for about 30 minutes, until tender and golden around the edges.

Transfer the roasted vegetables to a medium saucepan. If not roasting, cut the vegetables as described and place them directly in the saucepan.

Pour in 4–6 cups (1–1.5 litres) of water or vegetable stock over the vegetables, ensuring they are fully covered. Bring to a boil over high heat. Cook until the vegetables are completely tender.

Blend the soup until smooth.

Stir in the coconut milk and whisk to combine. Add chilli flakes and adjust the seasoning with more spices, salt, and pepper according to taste. If needed, adjust the consistency by adding more water or stock.

Swirl the reserved coconut milk on top and garnish with fresh chopped coriander.