1 c. elbow macaroni
1 tbsp. butter
1 1/2 c. milk
1 thin slice onion
1/2 tsp. salt
1/4 tsp. pepper
1/4 tsp. dry mustard
2 tbsp. flour
1/2 lb. cheddar cheese

Cook and drain macaroni. Put into buttered baking dish with 1 tablespoon butter. Mix to melt butter. Toss all other ingredients in blender in order given and blend well. Pour over macaroni; mix well. Bake at 350 degrees for 40 minutes or until browned and bubbly.