Preheat oven to 400°.
Cook pasta in boiling water 5 minutes or until almost tender. Drain and rinse with cold water. Place pasta in a large bowl.
Place bread in a food processor; pulse 10 times or until coarse crumbs form. Set aside.
Bring milk and bay leaves to a simmer in a small saucepan. Remove from heat; cover and let stand 5 minutes. Discard bay leaves. Lightly spoon flour into a dry measuring cup; level with a knife. Place flour in a small bowl; gradually add milk, stirring with a whisk until well-blended. Return milk mixture to pan. Cook over medium heat until thick, stirring constantly with a whisk. Remove from heat. Add cheeses, salt, and pepper; stirring until cheeses melt. Pour cheese sauce over pasta; stir well. Spoon mixture into a 13 x 9-inch baking dish coated with cooking spray. Combine breadcrumbs, sage, and butter in a bowl; toss with a fork. Sprinkle breadcrumb mixture over pasta mixture.
Bake at 400° for 20 minutes or until thoroughly heated.