Spray a 3 1/2 to 4 quart slow cooker with cooking spray. Put carrot in slow cooker. Sprinkle with salt, brown sugar, and butter.
Cover and cook on high (stirring every hour) for 3-4 hours until tender.
Spoon into serving bowl and spoon any sauce remaining over the carrots. Season with addition butter, salt, or pepper if desired. Sprinkle with parsley to serve.