I made snickerdoodles and doubled the recipe, but they came out flat and chewy, not puffy.
Sent by JoyceEditor: The culprit to your flat cookies was probably the baking soda or baking powder. It's one of the only ingredients that can't always be doubled along with everything else.
Use this standard ratio: for every cup of regular, all-purpose flour in your recipe, use 1 - 1 1/4 teaspoon of baking powder or 1/4 teaspoon of baking soda.
For snickerdoodles, keep in mind that some recipes intentionally over-leaven the dough so that the cookies puff and then collapse a little, giving them the signature crinkly top and chewy texture. If you like your cookies lighter and puffier, stick with the standard ratio of leavener to flour.
If the baking soda or powder already looks ok, you can try adding an extra egg white. This will help leaven the cookie and stabilize the structure.
Anyone else have advice on doubling cookie recipes?
Related: Help! How Do I Fix My Muffin Recipe?