Cook macaroni in boiling salted water until 'al dente'. Approximately 5-6minutes.
Meanwhile, in a small saucepan, melt butter. Stir in flour, salt, mustard,pepper and hot pepper sauce. Cook and stir until smooth.
Drain macaroni; combine with butter mixture in a large bowl and mix well.
Stir in milk and 2 1/2 cups of cheese.
Pour into an ungreased 2 1/2 quart baking dish. Cover and bake at 350degrees for 30 minutes or until bubbly.
Sprinkle with remaining cheese; let stand 5 minutes before serving.