Milk can help wash down failed baking experiments at home. But it can’t save you from turning up at a holiday party with tough, flat or, worse, fugly cookies. The F&W Test Kitchen’s Kay Chun, however, can help. Here, she explains how to avoid the most common mistakes. 1. Underbeating (a.k.a. undercreaming) the butter and sugar. The butter mixture should be pale yellow in color and fluffy, which takes about three minutes; this helps form tiny air bubbles so that during baking, the bubbles expand and help the cookies rise. 2. Overbeating (overcreaming) the butter and sugar. Stop once the butter is pale yellow and fluffy, otherwise the butter starts to break down and release all those air bubbles you’ve just created. During baking, the cookies will remain flat and dense. 3. Placing the cookies too close together on the baking sheet. Give the cookies enough space to spread. If there’s not enough room, bake the cookies in batches. 4. Overmixing the cookie batter. Overmixing activate