Because Marta Asked (aka demanded)

This recipe EASILY doubles and feeds an army. Tricks to success is to preheat the milk as you make the roux. I like using panko breadcrumbs for the top (nice texture).

From cooks illustrated: http://cooksillustrated.com/recipes/print/detail.asp?docid=6058

CLASSIC MACARONI AND CHEESE

Serves 6 to 8, or 10 to 12 as a side. Published May 1, 2004.

It's crucial to cook the pasta until tender--just past the "al dente" stage. In fact, overcooking is better than undercooking the pasta. Whole, low-fat, and skim milk all work well in this recipe. The recipe can be halved and baked in an 8-inch-square, broilersafe baking dish. If desired, offer celery salt or hot sauce (such as Tabasco) for sprinkling at the table.

INGREDIENTS

Bread Crumb Topping
6	slices white sandwich bread (good-quality, about 6 ounces), torn into rough pieces
3	tablespoons unsalted butter (cold), cut into 6 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)
5	cups milk (see note)
8	ounces Monterey Jack cheese , shredded (2 cups)
8	ounces sharp cheddar cheese , shredded (2 cups)
1	teaspoon table salt

INSTRUCTIONS

1. 1. For the bread crumbs: Pulse bread and butter in food processor until crumbs are no larger than 1/8 inch, ten to fifteen 1-second pulses. Set aside.

2. 2. For the pasta and cheese: Adjust oven rack to lower-middle position and heat broiler. Bring 4 quarts water to boil in Dutch oven over high heat. Add macaroni and 1 tablespoon salt; cook until pasta is tender. Drain pasta and set aside in colander.

3. 3. In now-empty Dutch oven, heat butter over medium-high heat until foaming. Add flour, mustard, and cayenne (if using) and whisk well to combine. Continue whisking until mixture becomes fragrant and deepens in color, about 1 minute. Gradually whisk in milk (pre-heat milk while making roux to expedite); 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.

   Here is where I add the macaroni and then place in baking dish. If making it the next day, return to room temp and then bake for about 45. If cooking immediately move on to #4.

4. 4. Transfer mixture to broiler-safe 9-by 13-inch baking dish and sprinkle evenly with bread crumbs. Bake at 350 for about 20-30 minutes. If top not entirely brown broil for about 2 minutes.