How to Make It
Cook pasta according to package directions, omitting salt and fat. Drain; keep warm.
Preheat oven to 350°.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and milk in a large saucepan over medium heat, stirring with a whisk. Cook 10 minutes or until thick, stirring constantly with a whisk. Remove from heat; add cheeses, stirring with a whisk until smooth. Stir in salt and black pepper. Add cooked pasta, stirring to coat. Spoon pasta mixture into a 13 x 9-inch baking dish coated with cooking spray.
Tear bread into several pieces. Place bread in a food processor; process until fine crumbs measure 1 1/2 cups.
Melt butter in a small skillet over medium heat. Add garlic; cook 30 seconds. Remove from heat. Stir in breadcrumbs until well combined. Sprinkle breadcrumb mixture evenly over pasta mixture. Bake at 350° for 25 minutes or until bubbly. Sprinkle with parsley.