Heat oil in a pot on medium heat. Add onion, garlic and fennel. Stir often so they do not burn. Cook until tender and beginning to caramelize, about 5-7 minutes.
Add the carrots and stock and spices. Bring to a boil, lower heat to a simmer and cover pot with a lid. Cook until the carrots are tender, about 20 minutes.
Remove from the heat and stir in the milk. Puree with an immersion blender or upright blender. If needed, add more milk to reach desired thickness.