I've Baked Thousands of Cookies—This Simple Trick Stops Bottoms from Burning

December is here, which means holiday baking has commenced. If you, like me, love to bake batches and batches of cookies for care packages and cookie swaps, you've likely found yourself in a conundrum of having too many cookies to bake and not enough oven space. And you've likely burned a cookie bottom or two, despite using a timer, digital oven thermometer, and following recipe directions precisely. It's a frustrating experience, but one you can avoid with a simple trick I picked up from my years of baking professionally: doubling up on your baking sheets.

Sturdy, thick, and well-made aluminum baking sheets conduct heat well, which makes them great for sheet-pan dinners, baking cookies, and roasting vegetables. But when the pan gets too hot, the bottoms of the cookies inevitably burn. Enter the trick of doubling up your pans: When you stack two baking sheets, you reduce the rate of thermal conduction, or how quickly heat flows. The bottom tray acts as a buffer for heat, absorbing and spreading it out. By the time the heat reaches the second tray, it's gentler and more diffused, allowing the bottom of your cookies to cook more slowly and evenly than those baked on a single sheet tray. 

Stacking your baking sheets also helps mitigate hot spots from your oven. Ovens can be fickle: Even if you're using a reliable oven thermometer, your oven likely has hot zones. In his article on the best rack to place a pizza stone on, former Serious Eats editor Kenji found that the bottom of an oven emits "an extraordinarily intense blast of radiant heat," which is why the bottoms of pizzas cooked in the lower third of the oven often scorch. The same applies to cookies.

Of course, keeping an eye on your cookies as they bake, rotating the baking sheet halfway through, and using a reliable oven thermometer are all key to preventing burned cookie bottoms.  But the next time you're worried about burning your cookie bottoms, do yourself a favor and just stack two sheet trays together. You'll have perfectly golden cookie bottoms with no scorching in sight.