Preheat your oven to 400°F (200°C). Spread the pumpkin chunks on a baking sheet and toss with 1 tablespoon of olive oil. Roast for about 25 minutes until tender and slightly caramelized, filling the kitchen with a warm, sweet aroma.
While the pumpkin roasts, dice the onion and mince the garlic. Heat the remaining tablespoon of olive oil in a large pot over medium heat. Add the onions and sauté for 5-7 minutes until they soften and become translucent, stirring occasionally.
Add the minced garlic and ground cinnamon to the onions. Cook for another 1-2 minutes until fragrant, stirring constantly to prevent burning. The mixture should smell warm and inviting.
Once the pumpkin is roasted and cool enough to handle, add the pumpkin chunks to the pot. Pour in the vegetable broth and bring everything to a gentle boil. Reduce the heat and simmer for about 10 minutes to allow flavors to meld.
Meanwhile, fry the sage leaves in a small dry pan over medium heat for 1-2 minutes until fragrant and slightly crispy, then remove and set aside. This enhances their aroma without bitterness.
Use an immersion blender to purée the soup directly in the pot until smooth and velvety. Alternatively, transfer the soup in batches to a blender and blend until creamy. Return to the heat if needed.
Stir in the warm heavy cream and season with salt and pepper to taste. If the soup is too thick, add a splash of broth to loosen it up, stirring gently to combine. Taste and adjust seasonings as needed.
Pour the soup into bowls and garnish with toasted pumpkin seeds and crispy sage leaves for added texture and aroma. Serve hot, enjoying the creamy, fragrant dish with a sprinkle of extra cinnamon if desired.