When baking cookies, which type of baking sheet reigns supreme: rimmed or flat?
Recently, we came across a piece of cookie-baking advice in the 1964 edition of Joy of Cooking: Use a flat, unrimmed baking sheet to promote even cooking. To see if this still applied to a modern oven, we made two identical batches of cookies: We baked one on our favorite cookie sheet, from Vollrath (its shorter sides boast a slightly raised lip to facilitate handling, but it has no true rims), and the other on our favorite rimmed baking pan, from Lincoln Foodservice, which features a 1-inch rim on all sides. We baked both batches successively on the same rack in the oven.
How evenly the cookies baked wasn’t an issue; both batches came out perfectly pale golden. However, the cookies baked on the rimless pan browned more quickly and finished baking several minutes before those on the rimmed pan. The discrepancy makes sense: Heat rises from the element at the bottom of the oven and circulates in currents to warm the entire chamber. A rimmed baking sheet’s raised edges block the hot-air currents, diverting them from the cookies to the top of the oven. A rimless baking sheet allows the hot air to immediately sweep over the cookies, which means quicker baking.
Bottom line: No need to rush out and buy a rimless sheet the next time you bake cookies. Just be aware of the type of baking sheet you’re using and the timing. We like to check on cookies a minute or two before the timer goes off, just to play it safe.