1Spray bottom of 2 1/2- to 3 1/2-quart slow cooker with cooking spray. Line side of slow cooker with foil; spray foil with cooking spray.
2In large microwavable bowl, place cauliflower and water. Cover tightly with microwavable plastic wrap. Microwave on High 4 minutes or until cauliflower is partially cooked; drain.
3Meanwhile, in 3-quart saucepan, mix soup, milk, salt and pepper. Cook over medium heat until smooth. Remove from heat; stir in cheese until melted. Add cauliflower; toss to coat. Pour into slow cooker.
4Cover; cook on Low heat setting 3 hours or until cauliflower is tender and sauce is thickened. Garnish with chives.