The number on an oven panel is a target setting, not a guarantee that every part of the oven is at exactly the same temperature. Many home ovens cycle above and below the target and have hotter areas.
Preheat until the oven cavity is stable
When the indicator light first switches off, the heating element may have reached its target while the oven walls are still absorbing heat. For many baked goods, allowing a few extra minutes after the oven signals ready can improve stability.
Learn your hot spots
If one side of a batch of cookies always browns more quickly, the oven may have a hot spot. Rotate the pan only when the recipe and product structure allow it, usually after the exterior has begun to set.
Use an oven thermometer
A simple oven thermometer helps compare the panel setting with the actual temperature. Record the average difference across several tests rather than relying on a single reading.
Rack position matters
A rack too close to the lower or upper element can darken the surface before the center is done. Start with the position recommended by the recipe and adjust after learning your oven’s characteristics.