Sharon e-mailed the Kitchen Shrink that her cookies always get dark on the bottom before the top begins to brown. She wondered what she can do to get them to bake evenly.
There are several things that affect the way cookies brown. The best way to get them to brown evenly is to bake them on light-colored baking sheets in the center of an uncrowded oven. Dark baking sheets hold the heat and brown the bottoms of cookies faster than do shiny aluminum or stainless-steel baking sheets. Insulated baking sheets practically insure that cookie bottoms will not get too dark. In the oven, heat is reflected from all sides onto whatever you are baking. The center of the oven is the best place for cookies to get even heat. If it appears that the tops aren’t browning well, move the baking sheet to the top shelf and the cookies will receive more reflected heat from the top of the oven. If the bottoms need more browning or the cookies are very thick, move the sheet to the bottom shelf. It is important to allow room around all the baking sheets so that the heat can circulate properly. If you are using a convection oven, it will circulate the heat more efficiently and bake your cookies faster. Never line the bottom of your oven with aluminum foil. While it makes cleaning easier, it reflects a lot of heat onto the bottom of your baking sheet and causes uneven browning.