Heat your oven to 200°C (390°F) and while it’s warming up, in a small bowl stir the Chinese five-spice powder, ground cumin, chilli powder and salt into 2 tablespoons of olive oil until well combined.
Lay the pumpkin wedges out evenly onto a baking tray and use a pastry brush to spread the spice oil onto all sides of each piece of pumpkin. Bake for 20 minutes, slide the tray out of the oven, turn all the pieces over and bake for another 20 minutes, by which time they should be soft and spices should be permeating your kitchen.
While the spiced pumpkin is baking, heat a tablespoon of olive oil in a pan until the oil is shimmering, then add the onions and fry until soft and translucent, add the minced garlic and ginger and fry for another minute, then transfer all to a soup pot.
Pour in the chicken stock, or vegetable stock if you prefer, and add the carrot slices, then bring to a simmer and leave to simmer until the pumpkin is finished.
By the time the pumpkin is done and is soft, the carrot should also be tender and the stock reduced. Turn off the heat and remove the tray of baked pumpkin, and set all aside to cool a little.
Slice off the pumpkin skins and transfer both the pumpkin pieces and carrot and onion in stock to a blender, and pulse for a few minutes until thick and creamy.
Return the spiced pumpkin soup to the pot, reheat, season with salt and pepper, taste, and adjust to your palate. If the soup is too thick for your liking, add more stock, cream or milk, stir in and reheat.
When your spiced pumpkin soup is ready, ladle the soup into bowls, add a dollop of sour cream to each, drizzle on the chilli oil, sprinkle on the crouton crumbs and chilli flakes, and garnish with fresh basil leaves or coriander sprigs, and serve immediately with crusty sourdough bread.