Why Are My Cookies Flat? (2024)

Are you one of those bakers that always remembers to soften butter before baking? To space cookies on sheet pans just as the recipe instructs? Or, chills cookie dough for the full requisite 2 hours—or, gasp, overnight? Well, I'm not one of those bakers.

In an effort to make as many cookies as possible, in as few batches as possible, with a limited number of baking sheets, I confess that I almost never give my cut-outs or balls the room they need. (What? Baking sheet real estate does notcomes cheap!) The result is almost always conjoined cookies, semi-circular once uncoupled (if uncoupled at all). Their misshapen looks a lasting reminder of my lack of patience and spatial awareness.

But before I go rearranging my cookie baking placement, buying sheet pans I don't need, or start proactively planning (gasp!) for softened butter needs, I think the question that needs answering most is: why do cookies spread, and how much power does a baker have, working within the confines of one recipe, to reduce that spreading? I did a few tests to figure things out—but first, the why of the matter.

There are several reasons why cookies lose their s#!t flop out, according to David Lebovitz, Deb Perelman, Dorie Greenspan, and others.

1. Greased cookie sheets promote spreading. Giving your cookies something with friction to cling onto, so to speak—like an ungreased baking sheet or one lined with parchment or Silpat—can slow the spreading. A greased sheet just encourages hot, melting cookie dough to run further.
2. Butter that's too cold. When a recipe calls for room temperature butter, you should be able to make a small indentation easily with your finger. If the butter is too cold and hard, you'll have to mix the cookie dough longer to get it to properly incorporate, which can lead to...
3. Dough that's too airy. As Dorie Greenspan explains in Dorie's Cookies, it's important not to take the first step of many cookie recipes—beating together the butter and the sugar—too far. The goal, usually, is to only incorporate the two ingredients without reaching the "light and fluffy" stage. When you mix the butter and sugar together at high speed or for too long, you'll aerate the dough excessively, causing the cookies to rise—and then fall—in the oven.
4. Dough that's too warm. Chilling solidifies the fat in the dough, which means that the cookies will melt slower under the heat of the oven. This results in taller, thicker cookies better at holding their original, formed shape. You'll see that, even when a recipe doesn't explicitly require it, many bakers recommend chilling cookie dough thoroughly—for at least two hours in the fridge— to slow spreading and to make the dough easier to work it (as in the case of cut-out or slice-and-bake cookies).
5. A wacky ratio of sugar, butter, and fat. Too much sugar, too much butter, or too little flour can all contribute to cookies that are on the run. (In the case of cookies that spread no matter how careful you are preparing the dough and/or the baking sheets, I'd probably turn to another recipe.)

I decided to futz with drbabs's Magical Marvelous Memorable Cookies to see if a few simple factors—chill time, oven temperature, and lining a cookie sheet—could really make a difference. I chose this specific recipe, one, because these cookies are known to spread (drbabs says so) and, two, because every time we've made them at the Food52 offices, they've turned out a little different. Just take a look at how much puffier the cookies on the right (which were made more recently) are than those in the original batch:

How would changing some simple variables affect how (and how much) the cookies spread (keeping in mind, of course, that each ball would sprawl slightly differently depending on the concentration and distribution of M&Ms, granola, pretzels)? I split one batch of cookies in four and baked each a little differently:

1. Baked at 375°F immediately after the dough was mixed, against the recipe's instructions.
2. Frozen for 20 minutes, then baked at 375°F, as the recipe recommends as an option.
3. Refrigerated for 1 hour, then baked at 375°F, as the recipe recommends as an option.
4. Refrigerated for 1 hour, then baked at 300°F, per a tip on King Arthur Flour's website that suggests stymieing spreading by baking the cookies at a lower temperature for a longer period of time. At a lower temperature, the cookies are able to set before the fat melts, their theory goes.

Using the June Oven, a super high-tech smart oven that has a camera inside of it, peering down on the food (it can detect when you've put in broccoli versus salmon versus brownies versus delightfully-chunky but problematic cookies), I was able to watch the cookies as they spread—and to automatically record each batch in a video saved to my phone (and then geek out over this bird's eye view I'd never seen before!).

Here's what I saw (and found, and tasted):

Cookies Baked Right Away

The cookies I baked immediately, without chilling at all, spread the most—though their movement was not detrimental to taste or appearance. This confirmed what drbabs warned against in his recipe, and why he called for a rest in the fridge or freezer. Fat in a dough not permitted to chill or solidify will encourage the dough to spread more readily.

A little less flat, these were still the cookies that most resembled the first batch we made at the Food52 offices (the photo on the left of the diptych above). That made me wonder: Perhaps I had creamed the butter and sugar less vigorously than had the original test kitchen baker, or was heavy-handed when measuring the flour. Or, maybe that same test kitchen baker had too not been a cookie angel, and baked that first batch without chilling the dough at all. Regardless of the reason, these cookies definitely emerged the thinnest and flattest of my four tests.

Cookies Baked After Chilling

The cookies that baked after 20 minutes in the freezer were the second flattest, noticeably thinner than those that spent an hour in the fridge. I had expected that the dough balls, frozen only for 20 minutes, would have spread less than the ones that had been refrigerated for an hour—but the dough must have not gotten quite as cold. More than degree of chill, time spent chilling seems to have had the largest impact on cookie spread. Had I frozen the dough for an hour, rather than just 20 minutes, might that have changed? It's likely. Regardless, both chilled batches spread less dramatically in the oven: Even 20 minutes has an impact.

Cookies baked after 20 minutes in the freezer (they hold their ball shape for a while, then spread rapidly):

Cookies baked after 1 hour in the fridge (they spread more consistently throughout the duration of the cook time):

Cookies Baked at a Lower Temperature After Chilling

The cookies that looked the most different from the rest were those baked according to King Arthur Flour's tip to bake at a lower temperature (at 300° F, as opposed to 375° F), and for much longer (25 minutes as opposed to 14).

This batch emerged blonde all over, with no thin, crispy circumferences. The lower the temperature, J. Kenji López-Alt of Serious Eats explains, "the more evenly the cookie bakes, with less of a contrast between the edges and the center." At the lower temperature, the cookies effectively slowly dry out and set.

Many cookie experts warn against a too-low oven temperature (David Lebovitz writes that it "can prolong the time it takes for cookies to bake, giving them too much of a head-start in the race against spreading"). But I found that the batch cooked at a lower temp held their shape best. So, it depends what kind of final texture and look you want: sometimes, a uniformly-textured, not-too-browned cookie cooked low and slow is what you want (like with shortbread). But other times (really, most times), the contrast between the crisp edges and ooey-gooey centers, that comes with baking for a relatively short time at a high heat, is what you're after (like these).

But, of course, it's ultimately the temperature of the dough that had the largest impact: Had the dough itself not been cold from the fridge when it went into the lower-temperature oven, the results surely would've been different.

And in the end, all the cookies were crunchy and crispy. While those that I baked at 300°F had a little more heft and chew in the middle, they were still brittle—they snapped in half with a hard crack, just like the batches baked at 375°F. Ultimately, the nature of the cookie did not change, no matter the chill time or oven temperature.

For kicks, I also tested parchment paper versus Silpat, putting both sheets in the same oven for the exact same period of time, rotating halfway through. The cookies on the Silpat-lined sheet did spread slightly more, but their bottoms were lighter. This is perhaps because of the nonstick, slippery coating on Silpat sheets, that, if you remember from above, encourage spreading. The parchment paper provided only slightly more friction to the cookies.

If, after all of this, you still find yourself with dough that spreads too much, Food52er butter-sugar-flowers has a wonderful suggestion: Drop the balls into a muffin tin (or a mini muffin tin) before baking. Uniform size, uniform thickness, and no risk of pancaked cookies. Another option is to scoop dough balls with a cookie scoop onto a baking sheet, freeze the sheet until the dough balls are thoroughly hardened, and bake straight from the freezer. Cold dough balls going into a hot oven will spread slower than room temperature, unrested dough balls.

Or seek out a cookie you know will be dense, thick, and chewy:

Or one destined to be very thin and crispy:

You could also embrace cookies that spread. Make a skillet cookie, or even better—One Big Cookie. Deliberately under-bake the first, not only allowing but admiring the way the cookie, warm and melty, runs onto your spoon. Let Dorie's vast cookie monopolize your baking sheet real-estate. Break it into organic, sculptural shards, and munch while you wonder why anyone ever cared about perfectly round puffies anyway.

Try a few tester batches yourself!

Determined to make drbabs's challenging cookie work? Experiment with chilling temperature and duration, cookie-scooping and freezing the dough, or baking at a lower temperature. Let us know what you find in your (delicious) tests.

Do you prefer cookies that are tall and domed or flat and squashed? And what steps do you take to get your cookies to cooperate? Tell us in the comments!