Throw all ingredients except milk and cheese into a crock cooker and cook on low until vegetables are very tender, about 4-6 hours.
Carefully pour mixture into work bowl of food processor fitting with steel blade or into blender container. Cover and process until smooth. OR, if you like it a little lumpy and bumpy like I do, use a potato masher and have at it in the crockpot itself--mash to your heart's delight.
Place your cauliflower mixture into a saucepan; stir in milk and cheese. Heat over medium heat, stirring constantly, until cheese is melted and mixture is hot.