In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté until softened, about 5 minutes.
Add the minced garlic to the pot. Sauté for an additional 1-2 minutes until it become fragrant.
Add the cubed roasted pumpkin and spices (cinnamon, nutmeg, cloves, cayenne, thyme, smoke paprika) to the pot and stir to coat the pumpkin in the spices.
Pour in the vegetable broth and bring the mixture to a boil. Reduce the heat to low, cover, and simmer until the pumpkin is tender, about 15-20 minutes.
Once the pumpkin is soft, use an immersion blender to blend the soup until smooth. If you don't have an immersion blender, carefully transfer the soup to a blender in batches.
Stir in the coconut milk and heat the soup through. Season with salt and pepper to taste.
Serve the vegan pumpkin soup hot, garnished with pumpkin seeds and a drizzle of coconut milk if desired.