In a large pot, heat the olive oil over medium heat. Add the diced onion and minced garlic. Cook until softened.
Add the pumpkin puree, vegetable broth, cinnamon, nutmeg, salt, and pepper to the pot. Stir to combine.
Bring the mixture to a simmer and cook for 15-20 minutes, allowing the flavors to meld
Use an immersion blender to puree the soup until smooth. If you don't have an immersion blender, you can use a regular blender, but be careful when blending hot liquids.
If desired, stir in the heavy cream for added richness.
Serve hot with a sprinkle of cinnamon on top.