True Mac

The worship of packaged macaroni and cheese has always been a mystery to me. Sure, we all grew up on that stuff, but have you tried it lately? The macaroni tastes like cardboard and the cheese sticks like glue. Memories are powerful, but there are some things that even nostalgia can’t overcome.

The really mysterious part of it is that homemade macaroni and cheese is almost as cheap and almost as easy to make. If you can make a white sauce, you can make macaroni and cheese, and anyone with a spoon and a saucepan should be able to make a white sauce.

Although it’s about as fashionable as a white belt these days, white sauce has a multitude of uses, ranging from cream soups to souffles and from croquettes to lasagna. That’s pretty cool, considering there are only three ingredients: butter, flour and milk.

What’s even better, given a little care, a white sauce is practically indestructible. Treat it gently in the early going--making sure the flour is well integrated into the milk--and then keep it from boiling. That’s all there is to it.

For most cooks, it’s their initiation into the alchemical part of the craft. Mix a solid and a liquid and you wind up with something in between.

In fact, scientists love it, though for different reasons than cooks do. To a scientist, it’s a nifty little puzzle. Here’s how it works:

Flour is a starch, and starches come in granules. Each granule of flour is made of concentric layers of two substances, amylose and amylopectin, that are held together by hydrogen bonds. (Don’t panic, that’s about as scientific as we’re going to get.)

When these starch granules are heated with a liquid, those hydrogen bonds begin to weaken and the granules break up. The first thing that happens is that some of the amylose breaks loose and floats into the liquid. This allows the liquid to penetrate the starch granule, swelling it and softening it further. This continues progressively: As the granule absorbs more liquid, more amylose breaks off. As more amylose breaks off, the liquid penetrates deeper into the starch granule, and so it goes.

Eventually, the sauce thickens because two things have happened. First, the starch granules have absorbed enough liquid to reduce the ratio of liquid to solid. Second, those little bits of amylose begin to bump into each other and link up. This forms a kind of soft network that captures the liquid within it.

You can see this process happening. First, and most obviously, you’ll see the liquid thicken and flow more slowly. You’ll also see the color--or more accurately, the quality of the color--change. Light shines very clearly through water and not at all through solid. As the solid disperses in the liquid, the sauce will gradually become cloudier and ultimately you will no longer be able to see through it at all.

But when a sauce is finished, there will be a remarkable change: It will turn shiny, since the starch has softened to the point that it is no longer blocking light. (If you were working with a pure starch and water, the sauce would be completely clear. It’s the odd bits of protein in the flour that make a white sauce white.)

But the dish is called macaroni and cheese, not macaroni and white sauce. Why do you need the sauce at all? You can find the answer to that question quite simply by trying to melt cheese by itself. All you’ll get is sticky clumps. Cheese is coagulated protein and, no matter how you cut it up, once it melts it begins to re-coagulate (oil is added to fake cheese or “cheese food” to prevent this; essentially it’s cheese and sauce in one).

The most vivid real-life example I can think of is what happens when you make pasta with cheese and butter. If you add the ingredients in that order, you’ll get pasta coated with sticky bits of cheese floating in melted butter. But dress the pasta in butter before adding the cheese and you’ll get a smooth, lightly coating sauce. The butter disperses the cheese and doesn’t give it a chance to regroup.

At this point in the story, you’re forgiven if you think you’ve stumbled into a chemistry experiment rather than a recipe. Here’s what it comes down to:

* Make sure the butter and the flour are a smooth paste before adding the milk. This will help prevent clumping. Also, when you add the milk, do it a bit at a time, whisking constantly.

* You’ll find people who say that the milk should be hot when it is added to the flour-butter paste. They are wrong. Certainly, the sauce will thicken faster that way but, in fact, it will cook too quickly; not all the starch will be converted and you’ll get lumps. To get the smoothest, most uniform sauce, add cold milk and take the extra five or 10 minutes.

* Once you’ve added the first part of the milk, you can raise the heat to thicken the sauce a little more quickly. Remember that milk scorches easily, though.

* Once the sauce is thickened, it will hold for a long time if you treat it right. Keep it over low heat and float a pat of butter on top. The butter will melt and prevent the top of the sauce from forming a skin (if the skin does form, whisk it into the sauce and increase the heat; it will reincorporate).

* Never boil the sauce; that will break down the binding ability of the starch.

Finally, in looking through many recipes for macaroni and cheese, it was interesting to see that there were two distinct schools of thought about how the noodles and the sauce should be mixed.

I’ve always tossed everything in a big bowl, mixed it up and then turned it out into a gratin dish for baking. But there is an alternate method recommended by several good cookbooks, including the classic 1953 “The Joy of Cooking.” These books recommend layering the macaroni and the cheese in the gratin dish and then pouring the sauce over.

We tried both methods in The Times Test Kitchen. The poured-over gratin was somehow saucier and a little cheesier than the one that was mixed together. I’ll stick with my way; it was a little cleaner and more elegant, though I’m certainly not doctrinaire about it.

After all, neither came from a box.

Macaroni and Cheese With Green Onions and Ham

Active Work Time: 25 minutes; Total Preparation Time: 1 hour 15 minutes

You can make this fancy by using a combination of different cheeses--I like a combination of Fontina with a little fresh goat cheese and some Parmigiano-Reggiano (they’re not very strong, so add the mustard to the white sauce). But the classic is good old American Cheddar.

6 tablespoons butter plus more for greasing pan

1/4 cup flour

3 cups milk

1 tablespoon Dijon mustard, optional

Salt and white pepper

1 pound dried short noodles, such as elbow macaroni

3/4 pound grated cheese

1/2 pound cooked ham, cubed

1 bunch green onions, sliced

1 1/2 cups fresh bread crumbs

* Make white sauce by melting 4 tablespoons butter in medium saucepan over medium-low heat. Add flour and whisk until smooth. Cook 5 minutes, stirring occasionally, to remove raw taste of flour. Add 1 cup milk and whisk until smooth. Raise heat to medium and add remaining milk, whisking occasionally to prevent lumping. Cook until sauce has thickened, about 10 minutes. Add mustard, if desired, and season to taste with salt and white pepper.

* Meanwhile, cook noodles in plenty of rapidly boiling, lightly salted water until barely tender, about 8 minutes. Drain, remove to large mixing bowl and toss with 1 tablespoon butter to prevent sticking.

* Add cheese to white sauce and stir to mix. Add cooked ham and green onions and mix again. Add white sauce mixture to cooked noodles and combine thoroughly. Turn noodles out into well-buttered 2-quart gratin dish.

* In small skillet, melt 1 tablespoon butter. Add bread crumbs and fry, stirring constantly, until lightly toasted, about 5 minutes. Scatter bread crumbs over top of noodles and bake at 350 degrees until top is browned and bubbling, about 30 minutes.

6 to 8 servings. Each of 8 servings: 589 calories; 1,401 mg sodium; 73 mg cholesterol; 24 grams fat; 57 grams carbohydrates; 35 grams protein; 0.25 gram fiber.