Cookies are delicate little things. They’re so small that baking them even 15 seconds too long makes a difference. Baking them too long makes them dry, hard, and less appetizing.

But how long should you bake them?

That depends. Look at all the factors that affect baking time:

• The heat of the oven
• The pan
• The shortening or butter on the pan
• The size of the cookies
• The uniformity of the cookies
• How many cookies are on the pan

The mission of precision baking is to control these factors so that you have perfect cookies every time, so that your cookies are baked within 15 seconds of the perfect time.

And the perfect time is when the bottoms of the cookies are baked to a light golden color, set but not brown.

This article will tell you how do that.

But first, let’s introduce you to exquisite cookies that are even better with precision baking.

1. Preheat the oven to the right temperature every time. Start heating the oven well ahead. It takes longer to heat than you think it does. That little indicator light that says the oven is now 350°F—it isn’t. That’s set on a timer, not a thermostat. The only way that you’ll know for sure is with an oven thermometer.
2. Make sure your oven is 350°F for every batch. Trust your thermometer. Your oven is not set at a constant temperature. It cycles. When your oven cools, it turns on and starts to heat. And then it stops, and it starts to cool. Check your thermometer. You may need to wait a couple minutes for the temperature to reach 350°F again.
3. Line your pans with parchment paper. I use two large, 11x17-inch baking sheets. (But I don’t put both in the oven at the same time; it’s too hard to bake both sheets evenly.) I load the second pan while the first is baking.
4. If you don’t have parchment paper, wipe the grease off your pan every time. Extra melted butter or shortening on your pan, will change how your cookies bake, how they spread, and how long they will need to bake. (Invest in parchment paper.)
5. Make your cookies all the same size. Use an ice cream scoop (usually a one-ounce scoop). Scoop and press the dough against the side of the bowl to eliminate any voids. Load them onto the parchment paper with room to expand.
6. Put the same number of cookies on the sheet every time. Twelve one-ounce cookies on a sheet is usually right. More cookies take longer to bake, and fewer cookies bake quicker. So, the same number of cookies is important. When you run out of cookie dough and you only have eight or ten for the last batch, set the timer for less time, a minute or two less. You’ll have to guess. The cookies are done when the bottoms are golden, not brown. Take one of the cookies from the oven, put it on a cooling rack, and hold the rack up to see the color of the bottom.
7. Bake them for the same time, every time. You’ll need a timer that will count the seconds, not one that only reads minutes. (Most timers don’t; use the timer on our microwave.) Fifteen seconds too long and your cookies are no longer perfect.
8. Get them off the pan immediately. They will continue to bake on the hot sheet. The easiest, quickest way to get them off the sheet is to set a cooling rack next the baking sheet, grab the edge of the parchment paper, and drag it off the pan onto the rack.