Cookie science: how to personalize your chocolate chip cookies

Good bakers know how to follow recipes. Great bakers know how to tweak them – how to deviate subtly from the printed word and create something that’s not just tasty but tailor-made to your palate. The line between good and great is surprising easy to navigate when it comes to chocolate chip cookies. All you need is a little cookie science and a friendly guide to show you the way.

In our case, that guide is Jocelyn, a top-notch baker who develops recipes in King Arthur Flour’s test kitchen. She knows that just a few simple changes can turn a regular chocolate chip cookie into one that’s extra-crunchy, extra-chewy, or extra-cakey.

Cookie Science via @kingarthurflour

I caught up with Jocelyn (with a very helpful assist from our own Dr. Andrea Brown) to understand the yummy science behind personalizing each batch of cookies.

For simplicity’s sake, let’s focus on Everyone’s Favorite Chocolate Chip Cookie, a new mix that Jocelyn developed for King Arthur Flour’s Essential Goodness line. She’ll share exact measurements for personalizing that mix, but the basic principles apply to pretty much any chocolate chip cookie recipe.

Cookie Science via @kingarthurflour

How to make extra-crunchy cookies

If you’re making Everyone’s Favorite Chocolate Chip Cookie, add 2 tablespoons granulated sugar and bake for 2 to 4 extra minutes.

What does the extra sugar do?

Although sugar may seem like a fairly simple ingredient, it plays a very important and complex role in cookie dough. It contributes to both texture and flavor in many ways: it melts in the heat of the oven to increase spread, and it creates little air pockets in the dough to expand and make cookies rise. Sugar also caramelizes and participates in Maillard reactions to add both color and additional notes to the flavor, and it recrystallizes upon cooling to give the cookies crispy texture.

Maillard reactions are when amino acids react with sugars to give you the brown color and caramelized flavor in baked goods.

When adding an extra two tablespoons of granulated sugar here, you increase the ratio of sugar to fat and flour in the cookie. This will result in a bit more spread, a larger surface area and more material to caramelize and react and, of course, a little bit of extra sweetness as well, which never hurts.

You may notice that the cookies won’t be crispy immediately out of the oven; that happens later. While the exact science of cookie cooling is still somewhat of a mystery, one theory is that as the molten sugar retreats to its crystalline structure and solidifies, the cookie becomes crispy as opposed to bendy. Working with that theory, we can then understand why the more sugar present to recrystallize, the more snap your cookie will have.

How does granulated sugar act differently than brown sugar?

Granulated sugar contains little to no “invert sugar,” which is what you find in the molasses or refiners syrup added to brown sugar. This invert sugar is actually single monosaccharide molecules that were created by breaking down the double disaccharide molecules that make up granulated or table sugar (sucrose). These monosaccharides possess different chemical properties that make cookies chewier, as we’ll see in the tip below.

Why the different bake time?

By adding extra sugar, you can bake the cookies to a slightly higher temperature without over-baking, which will allow for a crispier final cookie as well as deeper flavor development.

Why not just bake any version longer to get a crunchy cookie without added sugar?

While it’s certainly true that baking any cookie longer will cause it to have a firmer final texture, having the extra granulated sugar allows the cookie to maintain a tender, “snappy,” crisp texture (due to the properties discussed above), as opposed to a less enjoyable hard/crunchy texture.


Cookie Science via @kingarthurflour

How to make extra-chewy cookies

Add 2 tablespoons brown sugar.

What does extra brown sugar do to the dough?

While brown sugar is similar to granulated sugar in many ways, it has one major functional component that granulated sugar does not: invert sugar!

The two primary invert sugar monosaccharides found in brown sugar are glucose and fructose, which are actually bound together to make the disaccharide sucrose which is what Americans know as our standard white table sugar.

Compared to sucrose, invert sugars caramelize at a lower temperature, and absorb and retain more moisture; fructose is particularly hygroscopic, meaning it really loves to suck up and hold onto water.

Invert sugars also interfere with recrystallization upon cooling, which helps make cookies crisp. By holding that extra moisture and delaying the sugar’s recrystallization, brown sugar has the wonderful ability to give you a moist, tooth-packing, bendy cookie loved by chewy cookie fans around the world.

Does it make the cookie extra sweet?

While a particularly perceptive taster might be able to tell the difference in sweetness with the additional two tablespoons brown sugar, the overall sugar level increased by less than 20%; so it’s really just a delightfully sweet cookie at either level.

Do light and dark brown sugar work the same?

In fact, they do. The differences between light and dark brown sugar in terms of the amount or types of syrup used are usually minimal, even though you might expect otherwise given the significant difference in coloration.

Cookie Science via @kingarthurflour

How to make extra-cakey cookies

Add 2 tablespoons milk.

What does the extra milk do to the dough?

Although it may seem obvious, the most important role extra milk plays is adding a little more liquid. As cookie dough is very low hydration, that two tablespoons of milk has more of an impact here than it would in something with higher hydration, such as cake batter.

Milk is around 85% water – and that water will evaporate in the heat of the oven to form steam. This steam will migrate to air pockets created by the melting sugar grains.

As the steam gets hotter, it teams up with gases produced by the leaveners, expanding those air pockets. That expansion causes the cookies to puff and rise in the oven, creating an airy, cakey texture.

The moisture contributed by the milk will also increase spread and hydrate more of the starches in the flour. These hydrated (gelatinized) starches support the structure of the air pocket wall, keeping the cookies from collapsing once cooled. By holding more water, they also help keep the cookies softer over time.

Why milk and not water?

While milk is mostly water, those other little molecules in milk do serve a purpose. First, their presence means that there’s 15% less liquid being added to the dough, and this helps prevent the dough from spreading too far and turning into some less-than-ideal chocolate chip pancakes in the oven.

The proteins in milk – about 3% to 4% – will enhance Maillard reactions (as discussed above) and contribute many of the flavor notes that we recognize as “baked,” giving the cookies their roasted, toasted, and even sometimes nutty notes.

Finally, the fat and sugar from the milk also add extra tenderness and richer flavor.

Cookie Science via @kingarthurflour

Some extracurricular reading on cookies science

So there you have it – the cookie science behind transforming our standard chocolate chip cookie mix into crunchy, chewy, or cakey versions. I’m fortunate to be able to share the kitchen with King Arthur’s research and development team, and I have to say that I’m personally just blown away with how good they are at their jobs.

I also want to thank Paula Figoni for her awesome book “How Baking Work” and Harold McGee’s “On Food and Cooking.” Both were enormously helpful.

Happy Baking!

Gwen Adams

Gwen Adams grew up in northern New Hampshire, on top of a mountain, surrounded by nature and not much else. After graduating from Lyndon State College in 2010, Gwen sought a career that combined her passion for writing with her love of baking. She found ...


  1. Daniel

    My chocolate chip cookies are always to cakey, I’ve had flatter ones from other places but I don’t like my cakey CC cookies. This (thinker) cookie also brings out more C chip flavor which I like. Thanks

  2. Betty

    I am searching for an oatmeal cookie recipe using the King Arthur All-Purpose Baking Mix. Any suggestions? Thank you in advance.

    1. The Baker's Hotline

      Tracy, while coconut oil can replace butter in some instances, it’s tough to use it when the ingredients called for are at room temp. Coconut oil tends to be either melted or hard, rather than something soft in between. If you’re looking for a non-dairy substitute for the butter, we’d suggest something like Earth Balance’s Vegan Buttery Sticks instead. If you do want to experiment with coconut oil, take a read through the details of our fat substitute tests. The recipe used involves creaming, and is gluten-free, but the basic principles will hold. Mollie@KAF

  3. Lisa Kenton

    Susan, thanks so much for getting back to me so quickly. I am one very happy King Athuor Flour customer. I’ll report back my results after the holidays, just in case anyone else might benefit from the info. Thanks again.

  4. Lisa Kenton

    If I want to add inverted sugar to my cookies recipes, many of which,but not all, contain both white and brown sugar, how would I go about doing it? I read that 15 percent invert sugar would keep the cookies soft for up to 3 weeks. That info came from a patent/copyright for chocolate chip cookies. If I buy already inverted sugar, an sub in 15 percent, should I sub the white or the brown sugar. If I can get this to work it would be great. I make a huge amount of Xmas cookies. I’ll start freezing doughs in a couple of days. I usually make about 20 different recipes in double or triple batches. Fortunately, I work at a grocery store bakery 3rd shift and can portion my dough out on sheet pans, then rack them up and roll them in the sub zero freezer. After my shift, I put them in empty parchment lined cardboard cupcake trays, refill the cupcake box then keep them in the freezer until I’m ready to bake, which I also do at work. I spend a lot of money to make these cookies, lots of dried fruits, nuts, butter and booze. I even use over 3 cups of pure maple sugar in King Arthur’s Vermont Maple Sugar Cookies. I use about 8 of you recipes, and buy your flour all year when ever it is on sale. I’ve laid in about 30 pounds. Anyway, if I could extend these cookies “shelf life ” that would be beyond great for mailing to non local family and friends. Any info you could give would be deeply appreciated.😐

    1. Susan Reid

      Hi, Lisa. You are an ambitious baker! I’ve been known to crank out similar amounts around this time of year. What you use depends on the batter’s formula, also on the bake time. Slightly under baked will stay soft longer. For the invert sugar proposition (best for drop cookies like crinkles, chocolate chip, oatmeal, peanut butter), I would substitute by weight, and do so for the white instead of the brown sugar (brown sugar already has molasses in it, an invert sugar, so taking that away can take you in the opposite direction).

      Best way to test is to sneak up on it, as well. Make a single batch of one of your drop cookie recipes, and swap 2 tablespoons of your invert sugar for 1/4 cup (1 3/4 ounces) of white sugar. Bake one cookie. See how you like its texture. If you think the dough can support it or the cooled result isn’t soft enough, add 1 more tablespoon invert to the dough, mix well, and bake one more cookie to see how it behaves. In any event, I would hesitate to go over 3 tablespoons of invert for a 4-dozen batch of cookies. Every formula is going to behave differently, so you’ll have to give the baby steps treatment to all of them.

      For a rollout or crisp cookie, I would not go with invert at all; most of those are high enough in butter and shortbread-like that they benefit from a couple weeks’ worth of aging anyhow. I hope this helps. Susan

  5. Pamela Hart

    I am baking my cookies in commercial convection ovens 25 degrees lower than recipe says. I watch them until they get or start to brown around the edges and some even on top. However they are still doughy in the middle. What can I do so they bake all the way without getting to brown on the outside. I have the fans down to low also. Please help, Pam

    1. MaryJane Robbins

      HI Pamela,
      Sounds like a perfect time to get in touch with your local KAF professional flour rep for some one on one assistance. Give our team a ring at 877-523-5687 and they’ll be happy to help get you in touch with someone. ~MJ

  6. Emma


    French baker here (and I do thank you for the grams measurements which allow me to bake american recipes, as I hate baking with cups, no precision thus no reliance). As our brown sugar is not like yours : it is unrefined cane sugar. What is best to make them more chewy : fructose or glucose ? I already have glucose for marshmallows, meringues… so do I need to buy fructose ?

    Regards, and thanks again for your great recipes, I mean the lemon bliss cake, in a swirl bundt pan is always a success as it is not common in France !

    1. Susan Reid

      Bonjour, Emma, ça va? Unrefined cane sugar is likely a little lighter in color than our commercial brown sugars, but the principle is similar; there is some of the molasses left with the sugar crystals, instead of being taken out and added back as it is in the US. The chewiness you seek is caused by an invert sugar inhibiting recrystallization, and a touch of glucose is likely to get you there. In truth, any invert sugar will do the job; I have used a tablespoon of corn syrup in a cookie recipe with good results; also honey and maple syrup. I would try a couple of teaspoons of glucose in addition to your unrefined cane sugar; I think it will take you where you want to go. That and baking cookies just so the bottom is set (it should hold itself together when you pick one edge off the pan with a spatula at a 45° angle; if it can do that it’s done, regardless if the top looks underdone.) There will be enough carry over heat to set the top if you let the cookies stay on the baking sheet when you take them out of the oven. Hope this is useful. Bon chance! Susan

  7. Claudia

    I would rather not use vegetable shortening, but use only butter in my cookies. How can I tweak the recipe so my cookies are not so spread out and thin? I was afraid if I just added more flour they might be doughy. Should I just cut the amount of butter?

    1. The Baker's Hotline

      Claudia, to prevent your butter-based cookies from spreading, try adding a few additional tablespoons of flour to the dough and reduce the sugar by the same amount (2-3 tablespoons). The cookies won’t taste drastically different, but you’ll find the cookies hold their shape better. It’s also a good idea to chill the dough for at least 30 minutes before baking. Enjoy! Kye@KAF

    1. PJ Hamel

      Whoooops! Right you are, Ms. Tweetley. Thanks so much for your eagle eye — all fixed now. PJH

Post a comment

Your email address will not be published. Required fields are marked *