Preheat the oven to 450F/220C.
Cut the squash in half and scoop out the seeds, place on a roasting tray cut side down and roast until fork tender for 45 minutes.
While the squash is roasting, heat olive oil in a soup pot, add chopped onion and cook over low heat until softened but not coloured for 10 minutes.
Peel and quarter sweet potatoes and set aside.
Add minced garlic to the soup pot and cook while stirring for 1 minute.
Then add sweet potatoes, Thai red curry paste and coconut cream, stir to coat the sweet potatoes.
Add the stock and salt, turn the heat up and bring it to a boil, then turn it down and let simmer for 30 minutes.
When the squash is tender, take it out of the oven and let it cool for about 5 minutes or until it's safe to handle. Use a kitchen towel to prevent your hands from burning.
Scoop out the tender squash flesh out of the skin and add directly to the soup pot.
Cook the soup for 15 minutes longer.
Taste the broth and add more salt if needed. Make sure the soup is sufficiently seasoned. Sweet flavour of squash and sweet potatoes need salt to balance out the flavours.
Blend the soup with a hand blender for silky smooth texture.