The Science of The Chocolate Chip Cookie



There is no doubt in my mind that Chocolate Chip Cookies are the ultimate classic baked good and comfort food.  There is just nothing that compares to a warm gooey cookie right out of the oven.  And a few years ago I set out on a mission to develop the most perfect chocolate chip cookie recipe ever.  But this led to the question: What is my idea of the perfect chocolate chip cookie?  Well, I am all about contrasts.  So in my mind it needs lots of contrasts of textures and flavors.  And I created that for myself.  A thick, chewy on the inside crunchy on the outside cookie that has hints of caramel and salt with dark chocolate chips and toasted pecans.

I had the brilliant idea for customizable cookies according other people’s idea of a perfect chocolate chip cookie.  Thin and crispy with milk chocolate?  Cakey and puffy with peanut butter, cinnamon and dark chocolate? Whatever your little heart desired.  I became obsessed with the science of the cookie.


The other day somehow this topic came up with a co-worker of mine.  She told me she had been trying to make really thin, chewy cookies for some time now with little success.  Open the flood gates! My mind started racing trying to remember all of the things I researched about the science of baking and I immediately started using my formula to create this recipe.

For any other geeks out there that are as interested in the science of baking as I am, I introduce to you “Baker Bettie’s Rules for Customizable Chocolate Chip Cookies!”

We will start with the standard Nestle Tollhouse Cookie Recipe: 

  • 2 1/4 cups all-purpose flour
  • 1 tsp baking soda
  • 1 tsp salt
  • 1 cup butter, softened
  • 3/4 cup granulated sugar
  • 3/4 cup packed brown sugar
  • 1 tsp vanilla
  • 2 large eggs
  • 2 cups Nestle Toll House Chocolate Chips
You know the drill: Combine dry ingredients.  Cream butter and sugar.  Add the other wet ingredients.  Add the dry ingredients to the wet and the chips.  Bake in a 375 degree oven for 9-11 minutes.
This recipe creates a fairly standard cookie.  Slightly chewy, slightly crunchy. Not too flat, not too caky.  Fairly neutral.  So to create the kind of cookie you are looking for, you can manipulate each component of this recipe.

Flour: If you want a chewier cookie change out the all-purpose flour for bread flour.  Bread flour has more protein and therefore will create more gluten.  If you want a taller cookie with a lot of texture cut back the flour to 2 cups and add 1 cup of oatmeal flour.  You can find this in the grocery store or create your own by grinding old fashioned oats in a blender to a fine crumb.


Baking Soda/Powder: There is no baking powder in the original recipe but if you want taller and cakey cookies add 1 tsp.  Keep the 1 tsp baking soda. to learn more details about baking soda and baking powder and how to sub or eliminate them, check out this post. 

Salt: Salt is one of the ingredients that only affects the flavor.  You can reduce or increase this amount according to your own preference for the salty/sweet combo.  But don’t eliminate it completely! I usually increase it to 1 1/4 tsp and use kosher salt for a more coarse flake.

Butter: There are several things you do with the butter.  If you are wanting a nice chew to the cookie and have decided to opt for the bread flour, melt the butter.  The water from the melted butter will mix with the flour to create more gluten.  (I learned this from Alton Brown)  If you like a more complex caramel flavor to your cookie, brown the butter.  If you want a taller, cakey cookie, use shortening instead of butter.  You can use butter flavored shortening if you want to keep the butter taste, but some people prefer the flavor or regular shortening.  Shortening will also make a very soft cookie.

Sugar: The ratios of the white sugar to brown sugar are important to produce the kind of cookie you want.  Higher white sugar to brown sugar ratios will produce a more crisp and crunchy cookie while higher brown sugar to white sugar ratios will produce a more soft and chewy cookie.  Dark brown sugar will up the chewiness even more.  Play around with it to produce the texture you want!

Vanilla: Vanilla only affects the flavor.  Increase the amount up to 1 tbsp if you really like the flavor, or eliminate all together if you want a more buttery flavor.  You can also use mexican vanilla for a more unique flavor.  It almost has hints of cinnamon.

Eggs: Eggs puff baked goods so eliminate an egg if you want a flat cookie and keep both eggs if you want a taller cookie. Egg whites dry out baked goods so if you like a really crunchy cookie add another egg white.  Alternatively, if you prefer a moist chewy cookie eliminate one egg white or one egg altogether.  You can even add a little bit of milk to add more moisture in place of the egg.

Add Ins: This is where you get to let your creativity go.  When I offered my customized chocolate chip cookies for my business you had these options: milk chocolate chips, dark chocolate chips, bittersweet chips, butterscotch chips, white chocolate chips, peanut butter, cinnamon, oatmeal, cocoa powder (to make the whole cookie chocolate), cayenne, toasted pecans, toasted walnuts, raisins, orange zest, dried cranberries, and toasted coconut.


Other Tips: Higher cooking temps (375) will keep a cookie taller while a lower temp (325 or 350) will allow the cookies spread out more.  Chilled dough will also produce a taller cookie.  If you like really soft cookies, spray them with a bit of water before baking.

Things I Never Change: Always bake your cookies in small batches to produce even browning.  (I cook 6 at a time)  Always bake on foil or parchment paper so you can immediately slide the cookies off the baking sheet when they come out of the oven.  This way the hot pan won’t continue to cook the cookies.  Remove from the oven just when the edges are brown and not when the entire cookie looks cooked through.  They will be over cooked.  If at all possible, always rest the dough for at least an hour or overnight before baking.  This will give you a more evenly cooked cookie.  And ALWAYS use a scoop!


So using the rules stated above, I came up with a recipe for a thin and chewy cookie.  They were perfect.


What is your perfect chocolate chip cookie like?


Thin and Chewy Chocolate Chip Cookies

Thin and Chewy Chocolate Chip Cookies


  • 2¼ cups bread flour
  • 1 tsp baking soda
  • 1¼ tsp kosher salt
  • 2 sticks unsalted butter, melted
  • ¼ cup granulated sugar
  • 1½ cup dark brown sugar
  • 1 egg
  • 2 tbsp milk
  • 1 tbsp vanilla
  • 2 cups chocolate chips


  1. Combine the bread flour, baking soda, and salt in a medium bowl.
  2. Melt the butter slowly and Add to the bowl of a stand mixer fitted with a paddle attachment.
  3. Beat the butter, granulated sugar, and dark brown sugar until combined.
  4. Add the egg, milk and the vanilla and beat on medium slow speed until incorporated.
  5. With the mixer on low speed, gradually add the dry ingredients into the wet ingredients until all incorporated.
  6. Scrape down the bowl as needed.
  7. Add in the chocolate chips and mix until incorporated.
  8. Allow to rest for 1 hour.
  9. Preheat the oven to 350 degrees.
  10. Line baking sheets with foil or parchment paper.
  11. Using a large scoop, drop 6 dough balls onto each cookie sheet.
  12. Bake for 11-14 minutes, just until the edges are lightly browned.
  13. Slide the cookies on the foil or parchment off the cookies sheet as soon as they come out of the oven.
  14. The cookies will be just slightly crunchy on the edges when cooled. If you want a completely chewy cookie and can resist eating them right away, store in an airtight container overnight and the cookies will be very chewy and soft in the morning.


  1. elizabeth Shum says

    My favorite cookie is the really tall and ooey gooey butter cookies or any cookie that is oooey gooey and really tall like 1 1/2 to 2 inches or taller :) Would love to know how to get the like that. So moist and yummy!

    • Baker Bettie says

      The best way to get really tall cookies is to bake them at a higher temperature, such as 375 degrees F and to shape them into large golf ball size before baking. Bake them just until the edges are set. The cookie will set before the butter has enough time to melt and spread, resulting in a tall cookie.

  2. Hasti Best says

    Hi.Thank you very much for the recipe.
    There is an ice cream shop in LA ( ). They use some kind of cookies for ice cream.
    Would you help me to make them?
    Best Regards.

  3. Jenna says

    I’ve been trying to make flat and chewy cookies like yours, but with olive oil as the fat. So far, no luck. Mine always tend to turn out slightly taller than I want them to.
    I use 1/2 cup of olive oil, 2 cups of flour, 1 cup of brown sugar, 1/3 cup of white, and 1/2 tsp of baking soda.
    I just made them this way, and I needed to add 5 more TBS of flour just to be able to handle them. (I use my hands) / I baked them at 350 for about 8 min. They turned out fine but I want them chewier and flat like your pictures.
    Any suggestions? I’m afraid that if I add more oil, they would end up greasy. Do I need to adjust the sugar? Or maybe I added too much flour and should get a scoop..?

    • Baker Bettie says

      What is the reason you are using olive oil in these? I haven’t done any experimenting with olive oil and these cookies but my guess is that it is going to be extremely difficult to get your desired result. Part of the structure and chew comes from the fat as it is creamed with the butter and sugar. 1/2 cup of olive oil is about 1/2 the amount of fat normally needed for that amount of flour, but because it is liquid it will be way too runny if you use an entire cup. You could try to use more olive oil and chill the dough before baking them because that should make the dough easier to handle. Check to see if you oven is cooking hotter than it says it is and reduce the heat to let the cookies spread out before they set. I think you will get a much more desired result using a solid fat or a melted fat that becomes a solid when cooled.

  4. Kindabaking says

    Made the cookies, so far so good. My cookies weren’t flat- but I think I like it better that way. Thank you for the cookie recipe!


    • Baker Bettie says

      So glad you tried the recipe and liked it. My guess is that your oven may be cooking a bit hotter if they are not completely flattening out. But sounds like they worked the way you wanted them!

  5. Jessica Fairclough says

    I have a quick question, I live in england so for the butter we don't work in cups or sticks, can anyone tell me how much it is in grams, I'm ok with cups for everything else, its just the butter I'm stuck on, thanks.

  6. Jess says

    I have a quick question, I live in england so for the butter we don’t work in cups or sticks, can anyone tell me how much it is in grams, I’m ok with cups for everything else, its just the butter I’m stuck on, thanks.

      • Jess says

        Thankyou so much, i somehow converted it to 220g which would have been way to off, im trying the recipe tonight, really excited to try it against my own recipe to taste the difference.
        just one more question, when i first made a batch of cookies a while ago they were quite runny, kind of like a thick browney mix but this was because the battery compartment in my weighing scales wasn’t flush so the whole thing wobbled slightly which threw of all my measuring they were however the most amazing cookies i have ever tasted but since fixing the weighing scales i have never been able to recreate them, what can i do to make the batter runnyer, the cookies were also a little chewy and diddnt go hard and crunchy, the basic recipie i used was:
        115g butter
        50g caster sugar
        110g brown sugar
        1 egg
        170g plain all purpose flour
        pinch of salt
        225g chopped milk chocolate

        thankyou again for all your help

  7. Sharon Schraer says

    Great post, explaining all the different variations I have tried. I usually include some bread flour, some whole wheat to make me think they are healthier, sometimes oats and prefer chewy cookies. Somehow love making chocolate chip cookies better than all other types and there are usually some in the freezer ready to eat.

  8. Katie R. says

    Two summers ago I whipped up a batch of chocolate chip cookies before a 4th of July BBQ. I’m not sure what combination of butter/shortening baking soda/baking powder I used, but they were a HIT!!! They were chewy and moist and my husband has been raving about them ever since! For 2 years now I have been trying to re-create these phantom cookies…I found your post yesterday and made them last night. THESE ARE THE COOKIES! My husband was so excited that these turned out just like he remembered. I think he is going to make me lock this recipe in a safe so that we always have it! Thanks so much for your informative, fun, life-saving post!!! You rock Baker Bettie!

  9. Dawn R. says

    Is it possible for chocolate chip cookies to be sexy? That’s all I can think of when I look at the ones I made from your recipe. THESE are the cookies I have searched for my entire life. They are so chewy, and crispy, and shiny, and oozy. I’m fully convinced that the recipe books lie about their ingredients so you can’t actually make cookies as good as them. Thanks for all the great tips in a simple and straightforward blog. I love you.

    • Baker Bettie says

      Is that even a serious question. Of COURSE it is possible for chocolate chip cookies to be sexy. When are they NOT sexy? I’m so glad that this formula worked out for you! I love it when people are able to create their own recipe to their own taste. Amazing.

  10. Kimberly Dougan says

    Thank you! After reading this I was able to adjust my recipe and just made the best batch of chocolate chip cookies of my life!

  11. sonja says

    i followed your recipe but they didn’t turn out flat!! i’ve tried everything, so many recipes but they ALWAYS rise! what am i doing wrong?? (i’m from switzerland, maybe it’s got to do with the quality of the ingredients??) thanks for your help!

  12. says

    I had been looking for a good thin chocolate chip recipe and this is definitely it !!! I made these about a week ago and am going to make them again in the next day or 2. These are the best chocolate chip cookies I have ever eaten (besides my mom's from a long time ago.) They are chewy and crunchy at the same time. Positively the best !!!!!!!!! By the way, I followed the recipe exactly as written. Didn't change a thing.

  13. Jenn says

    Hi Bettie,

    If I want my cookies to be a bit fluffier should I just add an egg or will I then need to counter that with dry ingredients? Thanks!!!

  14. Angela says

    Hi Betty,

    I started to assemble ingredients for chocolate chip cookies and discovered, I bought the wrong baking soda (for the freezer) so I put everything away and scrubbed the kitchen from top to bottom (spring cleaning early)….advance to the next day and here I am.
    I love reading about the science of the chocolate chip cookie, my favorite cookie, when i want a cookie. I usually don’t eat sweets, HFCS, hydrogenated fats, sulfites, nothing processed, see where I’m going…mostly Organic. To make a long story short…I know, too late, I want to make a healthy organic cookie.
    Can I use stone ground wheat flour instead of all purpose, coconut palm instead of white and brown? …Ok, here is the recipe:
    3 cups all purpose flour……I want to use organic stone ground wheat flour
    1 1/2 tsp. baking soda……….would like to skip
    1 tsp. baking powder……….. if need to use, would I increase to 2 1/2 tsp. to make up for the b. soda.
    1 1/2 tsp. sea salt
    2 sticks unsalted oganic butter
    1 cup packed lt. brown suger and
    1 cup sugar…………………..would like to replace both sugars with 1/2 cup organic coconut palm sugar. ( a dark, very sweet sugar)
    2 lg. pasture-raised organic eggs
    1 tsp. organic bourbon vanilla
    8 oz. organic dark chocolate…. 80%
    I like crispy on the outside, chewy on the inside or, at this point, any cookie recipe that makes me think it’s good for me, and I can have all the time.
    Love your posts!!

  15. Stephanie says

    Thank you for the recipe! I’m excited to try different variations of this.

    I tried your recipe above and while the cookies are excellent (!!) they look really dark, almost as if they’re burnt. Is that because of the dark brown sugar? They also aren’t as flat as pictured. Any insights? Or maybe it’s the unbleached bread flour I used.

    Again, thank you for the wonderful blog post! Very informative.

  16. Diina Zaki says

    I followed the exact recipe but it turned out a very crispy cookie and too sugary and i dont know what went wrong? any idea? i ddint put baking soda but used baking powder.

  17. says

    This certainly wouldn't make your cookies too sugary, but baking soda is not a replacement for baking powder or vice versa.

    If interested in reading about the difference:

  18. says


    These are the cookies of my dreams I had been waiting for. A light crunch, chewy but not too much so. These are heaven. But I guess heaven comes at a price. This recipe made about 18 cookies. 2 sticks of butter divided by 18 cookies is… a mess of a lot of butter per cookie. I had to give a dozen away, else I would have eaten them all. But seriously. This recipe can win awards.

  19. E says

    These cookies are AMAZING! I made them yesterday and found that they were the best chocolate chip cookies I ever made! I am saving this recipe!

  20. Watson says

    I make the best chocolate chip cookies that anyone I’ve fed them to has tasted, but mostly what I mess with is the flavorings, not the flour, sugar, etc. I use the standard joy of cooking chocolate chip cookie recipe with the following alterations:

    add ~1 tsp of cinnamon
    replace 1 1/2 tsp vanilla with 1 tsp vanilla and 1/2 tsp almond extract
    use AT LEAST 2 cups of chocolate chips

    It’s really simple but the results are amazing.

  21. Demara Dawn Wig says

    …I followed your Thin and Chewy Chocolate Chips recipe to the letter (..with the exception of using margarine instead of butter, and 2 1/2 tsp baking powder instead of baking soda (..according to your ""..) and they did not flatten at all and sort of burned on the bottom..!! I am perplexed. :( I thought I had finally found the perfect 'flat and chewy' cookie. I will have to try again, and follow exactly… But would margarine instead of butter, or powder instead of soda change it that much..?? ..Or, make it not change.. They looked exactly like how I put them in! Still tastes SO GOOD, but I want them flat..!! ..Ideas..??

    • Baker Bettie says

      Yes! These changes would change it a lot actually! Margarine has a higher melting point than butter. When the butter melts it helps the cookie spread. With margarine the cookie will likely set before it has a chance to spread. Margarine also typically has less fat content than butter and this could lead to the burning. It is also possible that your oven is cooking too hot, which is a common problem. You could try turning it down 25ºF and see if that helps. Are you using a baking sheet that has a dark coating? That could also lead to problems.

      The substitution for the baking powder and baking soda information I posted in that post is really meant for a pinch situation. If you are wanting specific results you really can’t substitute the two. They are very different things. Substituting or leaving out will always change the results.

      My idea really is just to try the recipe as written. And possibly turning down your oven temp.


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