Classic Macaroni And Cheese

1. Pulse bread and 3 tablespoons 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.

CLASSIC MACARONI AND CHEESE WITH HAM AND PEAS
Add 8 ounces deli ham, sliced 1⁄4 inch thick, and cut into 1-inch pieces, and 1 cup frozen peas to cheese sauce along with pasta.

CLASSIC MACARONI AND CHEESE WITH KIELBASA AND MUSTARD
Add 1 finely chopped onion to melted butter in step 3 and cook until softened and lightly browned, 5 to 7 minutes. Add flour to onion and continue with recipe, reducing salt in sauce to 1⁄2 teaspoon. Add 8 ounces kielbasa, quartered lengthwise and sliced 1⁄2 inch thick, and 4 teaspoons whole grain Dijon mustard to cheese sauce along with pasta.