Needless to say, never ever try to bake good chocolate chip cookies with imitation chocolate chips. How to bake them You want the oven up to temperature when the first batch of cookies goes in, so it's necessary to preheat. If the oven interior is cooler than 375 degrees, the fat will likely melt before the starch and protein set. You'll have the best luck baking cookies on heavy-gauge shiny baking sheets. Dark pans absorb heat quickly and the bottoms of the cookies may burn before the top is cooked.
Thin pans can heat unevenly, causing some cookies to burn before others are done.
If your cookie sheets are dark, line them with aluminum foil. The cookie sheet should allow at least 1 inch of space between its edge and the oven wall, so that air can circulate. Otherwise, the cookies may burn on the bottom. Place only one sheet in the oven at a time, unless you have a convection oven that circulates the warm air. Stacking sheets impedes air flow and results in uneven baking.