Many cookie recipes ask bakers to take out a stick or two of butter out of the fridge and let them warm to room temperature before baking, since softer butter mixes into dough or batter more readily. However, cold butter can be actually better for recipes where you don't want too much air in the final batch of cookies.

Mixing cold butter into cookie dough evenly distributes small bits of fat that melt and form flaky layers in the oven, just like cold butter in pie dough. When you want cookies that are flaky rather than soft and chewy, use cold butter to help break through the chewy gluten that forms during the mixing process.

One way to add cold butter to cookies is to incorporate it into your premixed dry ingredients using a pastry cutter instead of a mixer. You can also use slightly chilled butter in the dough for easier integration, then place the finished dough into the fridge to allow the butter to set and harden up before baking.