Cook noodles according to package directions. Meanwhile, in a Dutch oven, melt 6 tablespoons butter. Stir in the flour, salt and pepper until smooth. Gradually add milk. Bring to a boil; cook and stir for 1-2 minutes or until thickened. Remove from the heat. Stir in the chicken, gravy and pimientos.
Drain noodles; toss with remaining butter. Stir into chicken mixture. Transfer to a greased 13-in. x 9-in. baking dish.
Cover and bake at 350° for 30-35 minutes or until bubbly. Combine the cheese, bread crumbs and melted butter. Sprinkle around edges of casserole. Bake, uncovered, for 10 minutes longer or until golden brown. Let stand for 10 minutes before serving. Yield: 12 servings (1 cup each).