Heat olive oil in a large heavy pot and add onions and 1 tsp salt to it.
Cover and cook over moderately low heat, stirring occasionally, until the onion is very soft, about 10 minutes.
Next add squash, cover with lid and cook for 20 minutes. Stir in between.
Add the tomato paste, ginger paste, turmeric powder, 1 tsp black pepper, cinnamon & nutmeg. Give a quick stir.
Now add vegetable stock and bring it to a boil. Reduce the heat and simmer until the squash is tender, 20 minutes. Let it cool.
Working in batches, puree the soup in a blender. Add heavy cream and 2 tsp harissa to the last batch. Return all of the soup to the pot and season with salt and black pepper.
Serve with dinner rolls or toasted bread. Enjoy!