Preheat the oven to 425° F and line a large, rimmed baking sheet with parchment paper.
Place the carrots on the baking sheet. Drizzle with 1 tablespoon olive oil and season with salt and pepper, then toss to combine. Roast in the preheated oven until the carrots start to caramelize and become fork tender, about 25 to 30 minutes, tossing halfway through.
Meanwhile, heat the remaining 1 tablespoon olive oil in a large pot over medium heat. Cook the onions until soft and translucent, about 5 to 7 minutes.
Add the garlic, ginger, coriander and turmeric and cook until fragrant, about 30 seconds. Add the vegetable broth and turn the heat to low until the carrots are done roasting in the oven. Transfer the carrots to the pot (reserve a few for topping the soup) and puree with an immersion blender (or regular blender, in batches) to desired consistency.
Stir in light unsweetened coconut milk and serve topped with fresh cilantro an crusty bread, if desired.