Spray 3 1/2- to 4-quart slow cooker with cooking spray. Cook and drain macaroni as directed on package, using minimum cook time. Place macaroni in slow cooker; immediately add butter and stir until melted.
Add evaporated milk, half-and-half, 2 1/2 cups of the Cheddar cheese, the cubed cheese, mustard, salt and pepper; stir to blend well.
Cover; cook on Low heat setting 2 to 3 hours, stirring once halfway through cooking time. During last 15 minutes of cooking, sprinkle with remaining 1/2 cup Cheddar cheese and the bacon.