In a large pot, heat a tablespoon of olive oil over medium heat. Add the chopped onion and minced garlic, and sauté until the onion becomes translucent.
Add the diced zucchini to the pot and cook for about 5 minutes, stirring occasionally, until the zucchini softens slightly.
Stir in the ground cumin and cinnamon, and cook for another minute to release their flavors.
Add the pumpkin chunks and vegetable broth to the pot. Bring to a boil, then reduce the heat to a simmer. Cover and cook for 20 minutes, or until the pumpkin is tender.
Using an immersion blender or regular blender, carefully puree the soup until smooth and creamy. If using a regular blender, work in batches and be cautious of the hot liquid.
Return the pureed soup to the pot. Stir in the coconut milk, and season with salt and pepper to taste. Heat the soup over low heat until warmed through.
Serve the pumpkin zucchini soup hot in bowls. Garnish with fresh cilantro or parsley, if desired.
Pair the soup with crusty bread or your favorite soup accompaniment for a complete meal.