Almost every single baking recipe starts with an instruction to preheat your oven. This step sounds so simple, but it is actually the single most difficult step in baking. Unless you have left an ingredient out by mistake or you’re dealing with a recipe that is flawed (i.e. an instruction has been left out), many baking problems are cause by incorrect oven temperature and can be solved by preheating your oven correctly to ensure that it has reached the temperature you need to bake. It sounds obvious, but I can attest to the fact that it is incredibly tempting to put a tray of unbaked cookies into the oven without having to wait for a preheat.
The first step to preheating an oven is to turn it on to the temperature you want it to be. In my old oven, this involved turning a dial. In my newer, more modern oven, this involves hitting a few buttons.
Step two is waiting at least 10 minutes (probably longer) and then checking your oven thermometer to see if the temperature is correct. This step is crucial. Older ovens don’t have indicators that tell you when the oven has reached the desired temperature, so you must rely on a thermometer. Newer ovens often have sound indicators that alert you the oven has been preheated – and they often have nothing to do with the temperature inside of the oven. A thermometer placed in the center of the oven (or close to it) is the only way to be positive that the temperature is correct.
Now you can place your unbaked cakes or cookies inside, but be aware that every time you open the oven door that the temperature will drop slightly. Ideally, you will leave the door closed until the product is almost fully baked to try to maintain that constant temperature.
Very common problems cause by an oven temperature that is too low include pie fillings that won’t set and crusts that are soggy, cookies that spread too much and cakes that sink in the center or never fully rise. Common high temperature oven problems include cracked cakes and cheesecakes and, of course, burned cookie bottoms and pie crusts.