Preheat your oven to 400°F (200°C).
On a baking sheet, combine the chopped carrots, diced onion, and minced garlic. Drizzle with olive oil, and season with salt, pepper, cumin, and coriander. Toss to coat evenly.
Roast the vegetables in the preheated oven for 30-35 minutes, or until the carrots are tender and slightly caramelized. Stir halfway through for even roasting.
Once roasted, transfer the vegetables to a large pot. Pour in the vegetable broth and bring the mixture to a simmer over medium heat. Let it cook for about 10 minutes.
Remove the pot from heat and use a blender or an immersion blender to puree the soup until smooth.
Stir in the heavy cream and adjust seasoning with more salt and pepper if needed. Warm the soup over low heat just until heated through.
Serve warm, garnished with fresh parsley if desired.