Location, Rotation, Consistency, Measurement

There are lots of subtle factors that influence how your cookies will turn out. Here are just a couple.

Ovens are like people. Every one is unique, but they share some common traits. They have hot buttons and hot spots. They only want you to put certain things in certain places. Attention must be paid!

For baking one of the things you need to know is the temperature in your oven. Yeah, you say, isn't that why it's got the little knobby thing with all the numbers? Sure, that's a good first order approximation of the temperature inside, but it's smart to be more sure of what's going on in there temperature-wise. The top rack is probably hotter than the middle or bottom, and the temperature near the bottom is probably more consistent overall. Ever have your cookies turn out a mix of burnt and raw? Temperature inconsistency is one possible reason for that. There are others, but we'll talk about them later.

First, you should know what the actual temperature is inside your oven. Buy a simple oven thermometer and you'll be more in the know. Spend some time to move it around your oven and see what it can tell you about hot spots, temperature fluctuation, and the accuracy of your oven's temperature controls. Move it from top to middle to bottom. Move it front to back, side to side. You might be surprised, and you'll certainly know more about the behavior of your oven than you ever did before - and possibly more than you care to know.

To compensate for those fluctuations you need to simply be attentive while baking. Examine the cookies only a few minutes (say, 5) into the baking time. Rotate the cookie sheets to maintain consistency. Swap sheets between racks.

Another vital element of making all your cookies come out right is their size. That is, it's vital that the individual cookies on the sheet have a consistent size and weight. Ensure this by using a Cookie Scoop or what the pros call a Disher. With no fuss and a quick scoop you've got uniform blobbies of dough on your trays much more quickly and cleanly than is possible with a mere spoon. And for heaven's sake don't use your fingers. If your cookies vary in size and weight then it's much more likely that some will be underdone while others burn.