The oven rule you should always follow when baking

Whether you're baking pork loin or a batch of extra-soft chocolate chip cookies, there's one fundamental rule you must follow: preheat the oven! It's an easily forgotten step, and you might be tempted to just put the dish in without waiting for the oven to heat up, but this is a big mistake.

When the oven is fully preheated, it ensures even cooking. For example, if you want to roast your vegetables perfectly, the consistent (and high) heat ensures that no areas are too hard or too soft. It also allows the vegetables to begin browning immediately. If the oven is cooler, they are likely to cook completely before caramelizing properly. Similarly, if the oven doesn't reach the correct temperature, the cooking time will vary from the recipe, making it difficult to calculate the exact moment to remove the food.

For laminated baked goods, cookies, homemade pizza dough, and puff pastry, uneven heat can cause the bottom to burn before the top browns, and too much butter to escape. Any preparation that needs to rise, such as frittatas, scones, and bread, benefits from intense heat. If the initial temperature is too low, the baked goods will be flat. Given all the benefits, it's worth waiting about 15 minutes to preheat the oven, but it's also advisable to consider buying an oven thermometer to ensure the actual temperature inside matches the selected setting.

Exceptions to the preheated oven rule

There are certain situations where preheating the oven isn't essential, but exceptions are few. You can experiment by baking some muffins, cakes, quick breads, and cookies in a cold oven. The results might be better, depending on what you're aiming for, but it's best to experiment with this method only if you're an experienced baker and have the time to take the risk. If you're interested in this method, look for recipes that specifically instruct you to do so, such as the Southern cake that doesn't require preheating.

Braised meats, baked beans, or slow-cooked vegetables are also largely unaffected. Since they cook for an extended period at a low temperature, the lower initial temperature doesn't significantly impact the final result. Another exception: starting cooking in a cold oven can be key to achieving perfect bacon. Finally, dishes that only require heating and light browning on top, such as macaroni and cheese or gourmet tuna casserole, won't be drastically affected if placed in the oven before it's fully preheated.