Creamy Stovetop Macaroni with a Buttery Crumb Topping

1. Prepare Bread Crumbs

Pulse the hearty white sandwich bread and the chilled butter in a food processor until it forms coarse crumbs, which typically takes about 10 to 15 pulses.

2. Cook Macaroni

Adjust your oven rack to the middle position and heat the broiler. In a large pot, bring 4 quarts of water to a boil with a tablespoon of salt, then add the elbow macaroni. Cook the pasta until it is tender, following the instructions on the package. Once tender, drain the pasta and set it aside.

3. Make Roux

In the same large pot, melt 5 tablespoons of unsalted butter over medium heat. Once melted, add the flour, dry mustard, salt, and cayenne pepper if you're using it. Whisk this mixture continuously for about a minute until it becomes fragrant and deepens in color.

4. Make Cheese Sauce

Gradually whisk in the 5 cups of milk, ensuring you do this slowly to prevent any lumps. Bring the mixture to a boil, then reduce the heat and let it simmer for 5 minutes, whisking occasionally, until it thickens. Remove the pot from the heat and whisk in the shredded Monterey Jack and sharp cheddar cheeses until they are completely melted.

5. Combine Pasta and Sauce

Add the cooked pasta to the cheese sauce, stirring well to coat the pasta evenly. Cook this mixture over low heat for about 5 minutes until everything is heated through and steaming.

6. Broil Crumb Topping

Transfer the macaroni and cheese to a 13 x 9-inch broiler-safe baking dish. Sprinkle the prepared bread crumbs evenly over the top. Place the dish under the broiler for 3 to 5 minutes, watching closely, until the topping is deep golden brown and crisp.

7. Cool and Serve

Let the casserole cool for about 5 minutes before serving.