Baking Perfect Cookies
DON'T FORGET TO PREHEAT: To keep cookies from spreading too much, it is important to expose them to an immediate blast of heat. It takes at least 15 minutes for a standard oven to reach the desired temperature.
USE AN OVEN THERMOMETER: Oven temperatures can be off by as much as 50 degrees. Always use an oven thermometer to tell you what’s really going on inside.