Heat the olive oil and butter in a large pot over medium heat. Add the onion and cook for 5 to 6 minutes, until soft.
Add the garlic, cinnamon, nutmeg and smoked paprika and cook for 1 minute, stirring.
Stir in the pumpkin, broth, brown sugar, salt and pepper. Bring to a simmer, then cook for 15 minutes, stirring now and then.
Blend the soup until smooth with an immersion blender, or carefully in batches in a regular blender with the lid vented.
Return the soup to low heat and stir in the cream. Heat through without boiling. Taste and add more salt if needed.