Macaroni Cheese

From Suzanne

2 tablespoons butter
1 small onion, finely chopped
2 tablespoons flour
1/2 teaspoon dry mustard powder
2 cups milk
salt
pepper
2 cups grated cheese
2 cups macaroni, cooked

Melt the butter in a saucepan. Add onion and cook until clear. Stir in flour and cook until frothy. Gradually add milk stirring constantly until sauce boils and thickens. Remove from heat. Season with salt and pepper to taste. Stir in half the cheese. Add the macaroni stirring to combine. Pour mixture into an oven proof dish. Sprinkle over remaining cheese and bread crumbs if wanted. Cook at 190 degrees C for 20 minutes or until golden and heated though. Chooped cooked bacon or ham can be added to the sauce if desired.