You can easily divide this recipe in half; use a 1 1/2-quart casserole dish if you do.

Serves 12

6 slices good-quality white bread, crusts removed, torn into 1/4- to 1/2-inch pieces

8 tablespoons (1 stick) unsalted butter, plus more for dish

5 1/2 cups milk

1/2 cup all-purpose flour

2 teaspoons kosher salt

1/4 teaspoon freshly grated nutmeg

1/4 teaspoon freshly ground black pepper

1/4 teaspoon cayenne pepper

4 1/2 cups (about 18 ounces) grated sharp white cheddar

2 cups (about 8 ounces) grated Gruyere or 1 1/4 cups (about 5 ounces) grated pecorino Romano

1 pound elbow macaroni

1. Heat the oven to 375 degrees. Butter a 3-quart casserole dish; set aside. Place bread pieces in a medium bowl. In a small saucepan over medium heat, melt 2 tablespoons butter. Pour butter into the bowl with bread, and toss. Set the breadcrumbs aside. In a medium saucepan set over medium heat, heat milk. Melt remaining 6 tablespoons butter in a high-sided skillet over medium heat. When butter bubbles, add flour. Cook, stirring, 1 minute.

2. Slowly pour hot milk into flour-butter mixture while whisking. Continue cooking, whisking constantly, until the mixture bubbles and becomes thick.

3. Remove the pan from the heat. Stir in salt, nutmeg, black pepper, cayenne pepper, 3 cups cheddar, and 1 1/2 cups Gruyere or 1 cup pecorino Romano. Set cheese sauce aside.

4. Fill a large saucepan with water. Bring to a boil. Add macaroni; cook 2 to 3 fewer minutes than manufacturer’s directions, until outside of pasta is cooked and inside is underdone. (Different brands of macaroni cook at different rates; be sure to read the instructions.) Transfer the macaroni to a colander, rinse under cold running water, and drain well. Stir macaroni into the reserved cheese sauce.

5. Pour the mixture into the prepared casserole dish. Sprinkle remaining 1 1/2 cups cheddar and 1/2 cup Gruyere or 1/4 cup pecorino Romano; scatter breadcrumbs over the top. Bake until browned on top, about 30 minutes. Transfer dish to a wire rack to cool for 5 minutes; serve.

To begin, you still need to make a white sauce. A generous amount of butter is melted in a large saucepan, and then flour is stirred into it to make a loose paste. After the flour has cooked in the hot butter, hot milk is whisked in. The starch from the cooked flour expands in the milk, creating a thick, creamy sauce. The starch binds the sauce, so that when the cheese is stirred in, the result is creamy and smooth, not stringy and curdled.

It is important to use pungent cheeses, such as sharp cheddar, mixed with a little Gruyere or pecorino Romano for extra bite, since the white sauce and pasta will absorb a lot of flavor. The type of cheese used will also affect the sauce’s texture: Sharp white cheddar produces the smoothest result; yellow and extra sharp cheddars can become grainy.

A good Italian brand of dried elbow macaroni will have the best consistency. Undercook your pasta so that it is the slightest bit crunchy (very al dente) in the center, then rinse it under cold water. This stops the cooking and washes off the excess starch. You might think that starch would be useful in further thickening the casserole, but it isn’t; as it bakes, that extra starch merely expands and lends a mealy texture to your sauce.

The pasta will finish cooking as it bakes. The sauce will bubble, seeping into the hollows of your macaroni. When the smell of butter and browning cheese makes your stomach growl, you’ll know the dish is ready to eat.