I just made this up.
Cut up 2 lb. carrots into chunks. Cook covered in as little water as possible till tender. Drain, reserving cooking liquid.
Slice one onion into a large soup pot. Saute onion slices in butter or olive oil till tender.
Place drained cooked carrot chunks in a blender and add half and half, milk or a combination, enough that you can blend the carrot chunks smooth. Add some curry powder, more or less to taste and blend some more. Add the sautéed onion slices and their drippings to the puree and continue to blend. Add the carrot cooking liquid. When the mixture gets to be of such volume that it’s too full for the blender, return it to the soup pot, and simmer and stir, adding milk or half and half as needed to thin it. Season to taste with salt and perhaps some white pepper. Do not boil; just simmer. Serve hot.