Preheat your oven to 425°F (220°C). Toss the peeled, seeded, and cubed pumpkin with 1 tablespoon of olive oil, salt, and pepper. Spread the cubes evenly on a baking sheet in a single layer.
Roast for 25-30 minutes until tender and caramelized on the edges, stirring halfway through for even cooking.
While the pumpkin roasts, heat the remaining tablespoon of olive oil in a large pot over medium heat. Add the chopped onion and sauté until translucent and soft, about 5 minutes.
Add the minced garlic and cook for another minute until fragrant, being careful not to burn it.
Once the pumpkin is roasted, add it to the pot with the sautéed onion and garlic. Pour in the vegetable broth, then stir in the ground cinnamon and nutmeg.
Bring the mixture to a gentle boil, then reduce the heat and let it simmer uncovered for 15 minutes to meld the flavors.
Carefully use an immersion blender to puree the soup directly in the pot until smooth and creamy. Alternatively, transfer the soup in batches to a countertop blender. Be cautious with hot liquids to avoid splattering.
Return the blended soup to the pot if needed. Stir in the heavy cream, and season with salt and pepper to taste. Heat gently until warmed through, but do not boil to prevent the cream from curdling.
Ladle the soup into bowls and garnish with freshly chopped parsley. Serve warm and enjoy!