Prepare the Oven and Baking Dish

1. Preheat the oven to 400 F (200 C) and lightly butter a 2-quart casserole. Set aside.

Prepare the Pasta

1. Cook the macaroni in boiling water with 2 to 3 teaspoons of salt following the package directions for al dente. Drain well.

Prepare the Sauce and Combine Ingredients

1. In the top of a double boiler** or heatproof bowl, combine the milk, salt, flour, and melted butter. Whisk until well blended. Place the pan or bowl over a pan of simmering water and cook, whisking frequently, until thickened. Add the pepper, dry mustard, and cheese; mix well and heat until the cheese is melted and the sauce is smooth. Taste and add salt as needed.
2. Combine the hot drained macaroni with the sauce and transfer to the prepared baking dish.
3. Toss the breadcrumbs with 2 tablespoons of melted butter and sprinkle over the macaroni.

Bake and Serve

1. Bake the casserole for 15 to 20 minutes or until hot and bubbling and the breadcrumbs are browned. 
2. Serve and enjoy!