Best Food Writing 2014 (26 page)

       
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The cookie cools.
Once it comes out of the oven, the process isn't over yet. Remember that liquefied sugar? Well as the cookie cools, that liquid sugar hardens up, which can give the cookie an extra-crisp, toffee-like texture around the edges. Meanwhile, the air inside cools, which causes the cookie to deflate slightly, though when fully baked, the structure lent by eggs and flour will help it retain some of its rise.

It's a simple technique that hides more complicated processes underneath. So how do you decipher what's going on? My first course of action was to test out these basic ingredients one at a time in order to determine how they affect the final outcome.

Butter

Butter is where most recipes begin, and it provides several things to the mix.

It keeps cookies tender
. When flour is mixed with water (such as the water found in eggs), it develops
gluten
, a tough, stretchy network of interconnected proteins that set up as they bake. Gluten can't form in fat, thus butter will inhibit its overall formation, leading to more tender results. The higher the proportion of butter to other ingredients, the more tender your cookie will be (and consequently, the more it will spread as it bakes). I found that a ratio of 1 part butter to 1 part sugar to .8 part flour was about right for a cookie that spreads moderately but doesn't end up cakey.

          
COOKIE FACT #1: MORE BUTTER = WIDER SPREAD AND MORE TENDERNESS

Butter is essential for
flavor
. Substituting butter with a less flavorful fat like shortening, lard, or margarine yielded sub-par cookies. Butter is about 80 to 83% butterfat, 15% water, and 3 to 5% milk protein. These proteins brown as the cookie bakes, adding nuttiness and butterscotch notes to the final flavor of cookies.

          
COOKIE FACT #2: BUTTER GIVES THE MOST FLAVOR

Because of shortening's different melting qualities (and the fact that it has no water content), shortening-based cookies come out softer but more dense than those made with butter.

How butter is incorporated can also
affect texture
. In the early creaming stages of making a cookie, cool butter is beaten until it's light and fluffy. During the process, some air is incorporated and some of the sugar dissolves in the butter's water phase. This air in turn helps leaven the cookies as they bake, giving them some lift. Melting butter before combining it with sugar and eggs leads to squatter, denser cookies.

          
COOKIE FACT #3: MELTED BUTTER = DENSER COOKIES, CREAMED BUTTER = CAKIER COOKIES

I asked myself: if browning milk proteins provide extra flavor to cookies, how could I boost that flavor even more?

My friend Charles Kelsey, the man behind the fantastic Brookline, MA sandwich shop Cutty's, developed a simple chocolate chip cookie recipe for
Cook's Illustrated
magazine back in 2009. In his recipe, he made the ingenious discovery that browning the butter before adding it to the mixture would give the cookies a much more pronounced nuttiness.

But this created some other problems. Since the butter can't get hot enough to brown milk proteins until all of its water content has evaporated,
brown butter adds no moisture to dough
. This produces a couple of interesting results. Without water, sugar that is mixed into browned butter cannot dissolve (sugar molecules are highly
hydrophillic
and will dissolve readily in water, but not in fat), which makes it subsequently more difficult for them to melt into each other as the cookie bakes. The cookies ended up missing out on some of that caramelized toffee flavor I was after.

          
COOKIE FACT #4: LESS DISSOLVED SUGAR = LESS CARAMEL FLAVOR

With less water, you also end up with less gluten development, thus a cookie made with browned butter is softer and more tender than one made with creamed or plain melted butter. Soft and chewy is good, but I wanted a slightly better balance.

          
COOKIE FACT #5: CREAMED BUTTER = LIGHTER AND FIRMER, MELTED BUTTER = DENSER AND CHEWIER

So how do I get the flavor benefits of browned butter while still allowing for sugar to dissolve and caramelize properly? The answer turned out to be in the eggs.

Eggs

Before we jump to the solution, let's take a quick look at what eggs have to offer in a cookie.

Egg whites
provide a good amount of water, as well as protein.
Egg proteins are particularly good at trapping and retaining bubbles of air or water vapor. The higher the proportion of egg white in a cookie, the more it rises during baking. Because of the extra water, you also get more gluten formation, which again leads to a taller cookie (provided you use enough flour to absorb that extra water). Other than the small amount in the butter, eggs are the main source of water in a cookie dough recipe.

Egg yolks
also provide some moisture and protein, but more importantly they provide a well-emulsified source of fat. When cooked, egg yolk forms a tender protein coagulum that can keep cookies tender and fudge-like. A high proportion of egg yolk leads to a more brownie-like texture in a finished cookie.

By keeping the total mass of egg added to a dough the same but altering the proportion of white to yolk, you can achieve a variety of textures.

          
COOKIE FACT #6: EXTRA EGG WHITES = TALLER COOKIES. EXTRA EGG YOLKS = FUDGIER COOKIES

Turns out that the combination I like best is actually a 1 to 1 ratio of egg whites to egg yolks, which conveniently is exactly how eggs naturally come. Ain't that something?

Going back to my initial problem of wanting the flavor of browned butter but disliking the way it prevented sugar from properly dissolving, I asked myself, what if I were to flip the script for these cookies: instead of creaming sugar and butter and adding eggs, why not beat together the eggs and sugar then add the butter?

I tried it, beating brown sugar, white sugar, and vanilla with whole eggs in a stand mixer until the mixture became pale, aerated, and ribbony, with a nearly completely smooth texture. To this, I added my browned butter, which instantly cooked the eggs and curdled them, turning the mixture into an oddly sweet and vanilla-y scrambled egg custard. Lesson learned: let that browned butter cool before adding it.

My next attempt with cooled brown butter fared better, but the finished cookies ended up with an oddly uniform texture and a relatively smooth top rather than the cragginess I'd been getting earlier.

Turns out that you actually want a balance between dissolved sugar and undissolved sugar to keep things texturally interesting.

          
COOKIE FACT #7: TOO MUCH DISSOLVED SUGAR = UNIFORM TEXTURE AND LESS CRACKING

I settled on beating half of the sugar with the eggs until it completely dissolved, then incorporating the rest when I added the brown butter. The degree to which the butter is cooled before adding it to the mix can also affect how well it holds air when being mixed with the eggs. Warm butter flows very easily and doesn't trap bubbles well. The cooler it is, the more viscous it becomes, and the better it can trap air. Even a few degrees can make a difference. By letting my browned butter cool down until it was almost at room temperature, it became firm enough to beat into the egg and sugar mixture without deflating it.

          
COOKIE FACT #8: THE WARMER THE BUTTER, THE DENSER THE COOKIE

In order to get my browned butter to chill a little faster and to add back some of the moisture that's lost in the browning process, I discovered that whisking an ice cube into it after cooking killed both birds with one stone.

Sugar

There's more to sugar than just sweetness! The type of sugar you use and its method of incorporation can have a profound effect on the finished cookies.
White sugar
is crystallized sucrose, a complex carbohydrate consisting of a fructose molecule and a glucose molecule linked together. It is mildly hygroscopic (that is, it likes to retain moisture), and relatively neutral in pH.

Brown sugar
is
mostly
crystallized sucrose, but also contains a good amount of glucose and fructose, along with trace minerals that give it its flavor and a slightly acidic pH. Glucose and fructose are far more hygroscopic than sucrose.

If you bake cookies that are made 100% with white sugar or brown
sugar, you can clearly see the difference in spread. This happens because the baking soda in my cookie recipe is a powdered base, and needs some form of acid to react with in order to create the bubbles that leaven the cookie. Slightly acidic brown sugar causes cookies to rise higher when baking, which limits their spread. You end up with a cakier end result. White sugar, on the other hand, adds no leavening power, so you end up with a cookie that spreads wide. Because white sugar-based cookies more readily give up moisture, they also end up more crisp.

          
COOKIE FACT #9: WHITE SUGAR = THIN AND CRISP, BROWN SUGAR = TALL AND MOIST

A mixture of the two provides a good balance, and as I noticed in my egg tests, dissolving too much sugar can lead to a texture that's too uniform. With sugar left in distinct grains, the pockets of melted sugar that caramelize within the cookie as it bakes remain irregular, giving the cookie more textural interest.

But brown sugar has another advantage over white: it caramelizes more readily, leading to more intense flavor. I wondered: could I bump up the intensity of the toffee flavor while still maintaining a good white and brown sugar balance by pre-caramelizing some of my white sugar?

I tried it, heating my white sugar up in a pot until it was a golden amber before adding cold butter to rapidly chill it and then incorporating it into my dough.

No dice. First off, it's a mess trying to scrape hot caramel out of a pan and prevent it from hardening into a single massive clump. Secondly, it made my cookies far too soft and chewy (I recalled that in the process of caramelizing sucrose, it breaks down into glucose and fructose, acquiring their hygroscopic properties).

A much simpler way was to blend only the white sugar with the eggs so that it was pre-liquefied, giving it a little jump start on caramelization, then adding in the brown sugar later on with the melted butter.

Incidentally, if you want the absolute chewiest, most uniformly textured cookies, try replacing some of the white sugar with corn syrup, a sugar that is even more hygroscopic.

You end up with wide, flat cookies that stay soft and flexible even when completely cooled. Not only that, but since corn syrup is made up of simpler sugars than granulated sugars, it caramelizes more readily, leading to darker overall color.

          
COOKIE FACT #10: CORN SYRUP = SOFT, WIDE, DARK, AND FLEXIBLE COOKIES

Corn syrup is so darn powerful, in fact, that even a small amount of it will completely alter the texture of your cookie.

Next up: baking soda and baking powder.

Leavening

Leavening—the introduction of air to the internal structure of baked goods—can come in many forms. In bread, it's the carbon dioxide produced by yeast. In a cream puff, it comes from expanding water vapor. In the case of cookies, we get it from egg proteins capturing expanding gases, creamed butter, and most importantly, chemicals, namely baking powder and baking soda. What's the difference between the two?

Baking Soda
is pure sodium bicarbonate—an alkaline powder (aka, a base). When dissolved in liquid and combined with an acid, it rapidly reacts, breaking down into sodium, water, and carbon dioxide.

Baking Powder
, on the other hand, is baking soda with powdered acids built right in. In its dry state, it's totally inert. But once you add a liquid, the powdered acid and base dissolve and react with each other, creating bubbles of carbon dioxide without the need for an external acid source. Most baking powders these days are
double acting
, which means that it contains two different powdered acids. One that reacts immediately upon mixing with water, and another that only reacts after it's heated, giving cakes and cookies a little boost early on in the baking phase.

Making cookies with varying degrees of both soda and powder, I found that baking powder generally produces cakier cookies that rise higher during baking, producing smoother, shinier tops, while soda yields cookies that are craggier and denser in texture

          
COOKIE FACT #11: SODA = CRAGGY AND COARSE, POWDER = CAKEY AND SMOOTH

Cakey cookies are not for me, and the brown sugar I was using in my cookies provided plenty of acid for the baking soda to react with. I landed on ¾ teaspoon as the right amount. Moreover, because the Maillard reaction takes place more readily in mildly alkaline environments, baking soda has a powerful effect on how rapidly foods darken and develop browned flavors. Browning is a good thing when it comes to cookies.

Flour

The main differences in flour varieties comes down to protein content. Cake flour contains a relatively low amount, which leads to less gluten formation. Cookies made with all cake flour will be very soft, almost mushy, even when you've cooked them to what would normally be a beyond-crisp stage. All-bread-flour cookies, on the other hand, come out ultra-chewy. Alton Brown has a recipe called The Chewy which utilizes this effect.