Serves 4 to 6

Ingredients

5 tablespoons unsalted butter

3 tablespoons unbleached allpurpose flour

2½ cups whole or 2% milk

Coarse salt

¼ teaspoon dry mustard (optional)

? teaspoon freshly grated nutmeg (optional)

? teaspoon freshly ground black pepper

3 cups grated extra-sharp Cheddar cheese

½ cup grated Parmesan cheese

1 pound elbow macaroni

1 cup coarse fresh bread crumbs

Directions

Step 1: Preheat the oven to 375°F.

Step 2: Melt 3 tablespoons of the butter in a medium, heavy-based saucepan over medium heat.

Step 3: Add the flour and whisk until smooth; cook 2 to 3 minutes, whisking frequently. Slowly pour in the milk, whisking vigorously. If the sauce gets lumpy, don't worry; just keep whisking until smooth.

Step 4: Lower the heat and simmer for 7 to 8 minutes, whisking frequently, until creamy and smooth. Add 1½ teaspoons salt, the mustard and nutmeg if using, and the black pepper.

Step 5: Take the pan off the heat and add 2½ cups of the Cheddar and half the Parmesan cheese. Whisk until the cheese is melted and the sauce is smooth.

Step 6: Taste and add more seasonings if you like. It should be salted well, as the sauce will flavor the macaroni.

Step 7: Meanwhile, bring a large pot of water to a boil, add 2 tablespoons salt, and boil the macaroni according to the package directions.

Step 8: Drain well, return to the pot, then toss with the sauce until thoroughly coated. Pile into a 13 by 9-inch baking dish or four 6-inch cast-iron skillets.

Step 9: Sprinkle evenly with the remaining Cheddar and Parmesan.

Step 10: Melt the remaining 2 tablespoons butter and toss with the bread crumbs; distribute over the macaroni.

Step 11: Bake until the topping is browned and the macaroni is hot, about 20 minutes. Let rest for about 10 minutes before serving.

Step 12: Note: While the classic is always welcome, try mixing things up on occasion by adding zippy green chiles or briny tuna. For a smoky green chile version, add 1 drained 4-ounce can diced mild green chiles before you put the macaroni in the baking dish. Mix 1 teaspoon smoked paprika with the crumbs and butter.

Step 13: For the “tuna melt” version, substitute 1 cup grated Havarti or Fontina cheese for 1 cup of the Cheddar when you make the sauce (you'll still need a total of 3 cups cheese plus the ½ cup Parmesan). Add 2 drained 5-ounce cans tuna and 2 teaspoons grated lemon zest to the macaroni before you put it in the baking dish.