Mistake: When cookies turn out flat, the bad guy is often butter that is too soft or even melted. This makes cookies spread. The other culprit is too little flour—don’t hold back and make sure you master measuring. Finally, cookies will also flatten if placed and baked on hot cookie sheets.
The most common cause is using a different flour than usual, such as cake flour, and measuring flour with too heavy a hand. Using larger eggs than called for can make cookies cakey, as will the addition of milk or more milk or other liquids than specified.
Butter contributes milk solids and water to a cookie, both of which soften it. Brown sugar contributes molasses – again, a softener. Using lower-moisture sugar (granulated) and fat (vegetable shortening), plus a longer, slower bake than normal, produces light, crunchy cookies.
Underbaked cookies are the secret to softness. Using cornstarch in the dough is another secret to softness, as well as the secret to thickness. Using more brown sugar than white sugar results in a moister, softer cookie. Adding an extra egg yolk increases chewiness.
A secret baker’s trick is to rest your cookie dough in the fridge. You can rest it for at least an hour, which will evaporate some of the water and increase the sugar content, helping to keep your cookies chewy. The longer you allow your dough to rest in the fridge, the chewier your cookies will be.
Yolks, where all of the fat is in an egg, increase richness, tenderness and flavor. Therefore, if you put an extra egg, you will get a chewier cookie. If you put less, you will get a more crumbly cookie.
Not Enough Flour
If your cookies are flat, brown and crispy, that means you need to add flour to your dough for the next batch. Though the culprit is usually a flour deficit, butter could also be to blame for this problem. Adding too soft or slightly melted butter to the dough can also result in flat cookies.
Why Do Cookies Get Hard? Like all baked treats, cookies are subject to getting stale. Over time, the moisture in the cookies evaporates, leaving them stiff and crumbly. The longer they sit, the more stale they become.
The heat of the oven will only dry them out more and make them hard as rocks. Microwaving them. If you cover your cookies with a wet paper towel and nuke them for a few seconds, they should soften up enough to eat.
Reasons cookies are browning too quickly and raw in the middle. Your cookies might be browning too quickly because of: your oven: it might not be preheating to the set temperature and might be going way above that or you are setting your oven to a very high temperature, too high for your cookies.
How do I know when flat cookies are done? If you are able to touch the top of them and they are right between soft and firm (or how you would prefer them), they would be good. if you are able to touch them and they still feel to dough-like, leave them in the oven for another 2 or 3 minutes.