Serves 6 to 8
It's crucial to cook the pasta until it's tender-that is, just past the al dente stage. Whole, low-fat, and skim milk all work well in this recipe. The recipe may be halved and baked in an 8-inch square broiler-safe baking pan. If desired, offer celery salt or hot sauce for sprinkling at the table.
6 slices hearty white sandwich bread, torn into quarters
8 tablespoons unsalted butter, 3 tablespoons cut into 6 pieces and chilled
1 pound elbow macaroni
Salt
6 tablespoons all-purpose flour
1½ teaspoons dry mustard
¼ teaspoon cayenne pepper (optional)
5 cups milk
8 ounces Monterey Jack cheese, shredded (2 cups)
8 ounces sharp cheddar cheese, shredded (2 cups)
1. Pulse bread and chilled butter in food processor to coarse crumbs, about 10 pulses; set aside.
2. Adjust oven rack to lower-middle position and heat broiler. Bring 4 quarts water to boil in large pot. Add pasta and 1 tablespoon salt and cook, stirring often, until tender; drain pasta.
3. Melt remaining 5 tablespoons butter in now-empty pot over medium-high heat. Add flour, mustard, 1 teaspoon salt, and cayenne, if using, and cook, whisking constantly, until mixture becomes fragrant and deepens in color, about 1 minute. Gradually whisk in milk; bring mixture to boil, whisking constantly. Reduce heat to medium and simmer, whisking occasionally, until thickened, about 5 minutes. Off heat, slowly whisk in cheeses until completely melted. Add pasta to sauce and cook over medium-low heat, stirring constantly, until mixture is steaming and heated through, about 6 minutes.
4. Transfer mixture to 13 by 9-inch broiler-safe baking dish and sprinkle with bread-crumb mixture. Broil until topping is deep golden brown, 3 to 5 minutes. Cool casserole for 5 minutes before serving.
