1/4 c. butter
1/4 c. unsifted flour
1 tsp. powdered mustard
2 1/2 c. milk
3 c. coarsely grated sharp cheddar cheese
1/4 tsp. salt, to taste
1/8 tsp. pepper
1 tbsp. Worcestershire sauce
1 tbsp. finely grated yellow onion, optional
1/2 lb. elbow macaroni, cooked and drained

Melt butter in a saucepan over moderate heat; blend in flour and mustard, slowly stir in milk. Cook, stirring until bubbly and thick. Mix in 2 cups grated cheese and remaining ingredients except macaroni. Taste for salt, add if needed. Cook and stir until cheese melts. Remove from heat; mix in macaroni. Turn into a buttered 2 quart casserole; sprinkle with remaining 1 cup cheese. Bake uncovered in preheated 350 degree oven about 1/2 hour until bubbly and lightly browned.