Set crockpot on High.
Spray or butter crockpot. Place velveeta and butter in crockpot and let melt. Meanwhile, boil water and cook noodles. Once most of the mixture is melted add cooked noodles, carnation milk, and regular milk. Set crockpot to low and cook for 1 to 2 hours, stirring macaroni every 45 mins or so. Serve when Mac n cheese is creamy!