|Bread Crumb Topping|
|6||slices white sandwich bread|
|3||tablespoons unsalted butter (cold), cut into pieces|
|Pasta and Cheese|
|1||pound elbow macaroni|
|1||tablespoon table salt|
|5||tablespoons unsalted butter|
|6||tablespoons all-purpose flour|
|1 1/2||teaspoons powdered mustard|
|1/4||teaspoon cayenne pepper (optional)|
|8||ounces Monterey Jack cheese , shredded (2 cups)|
|8||ounces sharp cheddar cheese , shredded (2 cups)|
|1||teaspoon table salt|
1. For the bread crumbs: Pulse bread and butter in food processor and set aside.
2. For the pasta and cheese: Boil 4 quarts of water; add macaroni and 1 tablespoon salt; cook until pasta is tender. Drain pasta and set aside.
3. In large saucepan (used to boil the noodles) heat butter over medium-high heat until foaming. Add flour, mustard, and cayenne and whisk well to combine. Continue whisking until mixture becomes fragrant and deepens in color, about 1 minute. Gradually whisk in milk; bring mixture to boil, whisking constantly (mixture must reach full boil to fully thicken). Reduce heat to medium and simmer, whisking occasionally, until thickened to consistency of heavy cream, about 5 minutes. Off heat, whisk in cheeses and 1 teaspoon salt until cheeses are fully melted. Add pasta and cook over medium-low heat, stirring constantly, until mixture is steaming and heated through, about 6 minutes.
4. Transfer mixture to broiler-safe 9-by 13-inch baking dish and sprinkle evenly with bread crumbs. Broil until crumbs are deep golden brown, 3 to 5 minutes, rotating pan if necessary for even browning. Cool about 5 minutes, then serve.