1. Preheat the oven to 425°F.
2. Peel and mince the ginger. Roughly chop the roasted carrots, discarding any stems.
3. In a medium pot, heat the oil over medium heat until shimmering. Add the ginger and carrots and cook until warmed through, about 3 minutes. Add the coconut milk and vegetable stock and stir to combine. Increase the heat to high and bring to a boil, then reduce the heat to medium and simmer until the liquid is thickened, 15 to 20 minutes.
4. While the soup simmers, place the leftover chickpeas on a baking sheet and warm in the oven to re-crisp, about 10 minutes.
5. Use an immersion blender to blend until smooth. (Or transfer to a blender or food processor and blend, taking care to avoid splattering.) Taste and add salt and pepper as needed. Serve garnished with the crispy chickpeas.