Why oh why oh WHY did my beautiful sheet of chocolate chip cookies turn into a big, ugly blob as they baked?

Well, there are several reasons cookies spread.

A touch too much sugar, for one – sugar is hygroscopic; it absorbs liquid. When you're preparing your dough, it may LOOK just fine (as the sugar is holding onto the liquid); but once it bakes, and the sugar releases that liquid it had been hoarding, watch out for those puddles!

Another less common reason is scooping cookie dough onto a hot baking sheet, or one that's overly greased. The dough hits the hot/slick surface, and starts to spread immediately; the additional, planned-for spread in the oven is exacerbated by this head start.

Frank, our veteran chef and test kitchen baker, recently sent me photos from an experiment on cookie spread he'd just conducted.

Says Frank, "We're working on different aspects of cookie baking, and thought you might enjoy these test results. The primary difference between these two trays [photos below] is the baking temperature.

IMG_0655

One reason cookies spread: oven temperature

"The failed tray baked at 350°F for 14 minutes.

IMG_0656

"For this practically perfect tray, we dropped the temperature to 300°F, and extended the baking time: 22 minutes for chewy, 30 minutes for crisp.

"This is a good example of showing temperature as ingredient."

Because the fat in cookies is a big part of their structure, prior to baking. Scoop the dough onto the baking sheet, and the fat is at least partially responsible for them holding their shape.

Once those cookies hit the oven, though, the fat starts to soften and melt. And the hotter the oven, the more quickly it melts. If the oven's hot enough, the fat melts before the cookies set. And since their flour/liquid matrix hasn't yet had a chance to harden, the cookies spread – becoming those dreaded cookie blobs.

This also might be one answer to a common question we hear on our baker's hotline: “Grandma gave me the recipe herself; why don’t my cookies look like hers?”

The quirkiness of different ovens, especially those from different generations of bakers, notes Frank, is "one of the many dangers of believing that a handwritten heirloom recipe must be correct."

Do you have a favorite cookie recipe that spreads too much? Try lowering the temperature, and baking the cookies longer; this trick just may give you the perfect treat you're after.

Want more tips and tricks for cookie baking? See all of our cookie skills blog posts. 

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About PJ Hamel

PJ Hamel grew up in New England, graduated from Brown University, and was an award-winning Maine journalist (favorite topics: sports and food) before joining King Arthur Flour in 1990. Hired to write the newly launched Baker’s Catalogue, PJ became the small but growing company’s sixth employee. PJ w...
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Comments

Anna

February 8, 2024 at 10:12am

I have a similar issue with shortbread that contains only fat, flour, and sugar. I have made this recipe before successfully, but this one turned into puddles of sand! The result was not even a unified cookie that could be scraped up...truly a baking sheet covered in sand. The single big difference is that I browned the butter (and re-solidified) before creaming with the sugar. Is it possible there was not enough moisture in the dough for a gluten matrix to form? If not that, any suggestions to improve? I don't mind adding an egg, xanthan gum, psyllium, or any other additives. No dietary restrictions and plenty of exotic ingredients at my disposal.

Maranda at King Arthur

February 8, 2024 at 4:53pm

Hi Anna, it definitely sounds like something was off with the ingredient ratios. Be sure to measure your ingredients carefully. When you choose to brown butter in a recipe, you must weight/measure the butter again after browning to make sure you still have the correct amount after evaporation. We are always happy to help on our Baker's Hotline if you have any additional questions. We can be reached at (855) 371-2253 (BAKE)!

Lin Lin

April 19, 2020 at 11:44pm

Some sites state the reason for spread is your oven isn't hot enough. A lower temp might allow the butter more time to melt before the cookies set.
I've also noticed that my 3rd-4th batch of dough (sitting on the counter, not fridge) doesn't spread as much as the first.
Any thoughts on why that could be?

Annabelle Shippee

May 20, 2020 at 3:48pm

Hi Lin Lin, that could potentially because the sugar has already had a chance to dissolve in the dough as it's sat, so it isn't dissolving from the heat of the oven and spreading quickly. 

Ruth

April 29, 2019 at 3:03pm

My problem is the opposite. I WANT my cookies to spread more than they do. It's just my preference, but that's the way I like them. I haven't been able to find a site that tells me how to do this.
The Baker's Hotline

April 29, 2019 at 3:15pm

Hi Ruth! You can always flatten them yourself before baking, but a common reason cookies don't spread well is if there's a little too much flour accidentally packed into the measuring cup while mixing the dough. This is very easy to do because flour likes to pack itself down so we recommend measuring by weight to prevent the problem entirely or, if measuring by volume is the only option, using the fluff, sprinkle, scrape method shown here. Another reason cookies won't spread is if there's very little sugar and/or very little fat, so it's possible that it's just the style of recipe that isn't giving you the results you'd like. Annabelle@KAF
Chris

March 17, 2019 at 8:32pm

My mom went to college for Culinary and also worked as a school lunch cafeteria manager/baker. She started having trouble with cookies spreading to thin when baking and started troubleshooting as nothing had changed. Same oven, same ingredients, etc. What she found was that Parkay Margarine had modified their product so that it had a higher water content. She switched to Land O'Lakes margarine with a lower water content and that solved her problem.
Megan Olson

March 17, 2019 at 2:20pm

I made what was suppose to be gooey choc chip cookies. I followed the directions to a tee. Yet, they stayed in a heap, meaning they didn't flatten at all. They baked in the same position they went in. They're good, but not flat. What's wrong? When recipes say "middle wrack: i'm using the third slip in the oven. I have six slips, so i imagine it's the third for "middle wrack". Am i incorrect? Checked the date of my ingredients and all show good to June 2019. Need someone's help. This is becoming expensive for me.
The Baker's Hotline

March 18, 2019 at 10:49am

The third rack sounds right to us, Megan! If you've made this recipe before and they spread, then there might have been more flour added this time. (It packs itself into cups so it's a pretty unreliable form of measurement sometimes.) If you haven't made this recipe before, it might just be the style of cookie that needs to be flattened before you put them in. Annabelle@KAF

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