Perfect Baked Macaroni and Cheese

1. For the topping: process the bread and butter in a food processor fitted with the steel blade until coarsely ground, about six 1-second pulses; set aside.
2. For the macaroni and cheese: adjust an oven rack to the middle position and preheat to 400 degrees. Bring 4 quarts of water to a boil in a dutch oven over high heat. Stir in 1 tablespoon salt and the macaroni; cook, stirring occasionally, until al dente, about 5 minutes. Drain the pasta and leave it in the colander; set aside.
3. Wipe the pot dry. Add the butter and return to medium heat until melted. Add the garlic, mustard, and cayenne; cook until fragrant, about 30 seconds. Add the flour and cook, stirring constantly, until golden, about 1 minute. Slowly whisk in the chicken broth and milk; bring to a simmer and cook, whisking often, until large bubbles form on the surface and the mixture is slightly thickened, 5 to 8 minutes. Off the heat, whisk in the cheeses gradually until completely melted. Season with salt and pepper to taste.
4. Add the drained pasta to the cheese sauce and stir, breaking up any clumps, until well combined. Pour into a 9 x 13″ baking dish and sprinkle with the bread crumb topping. Bake until golden brown and bubbling around the edges, approximately 20 minutes. Remove from the oven and cool for 10 minutes before serving.

(Recipe adapted from Cook’s Illustrated.)