Staggering and Rotating During Baking
Here are some simple basics that go a long way toward avoiding common baking mistakes.
When baking more than one cake pan at the same time, allow for some space between the pans and between the pans and the oven walls. Also, stagger their placement in the oven so that air can circulate and the cakes will bake evenly.
Even calibrated ovens have hot and cool spots, with temperatures falling within a 50-degree range. Cookies, pies, tarts, and all but the most delicate cakes should be rotated during baking to achieve even browning and baking. The halfway point or shortly thereafter is generally a good time to rotate. If you have one pan on the bottom rack and another on the top, switch their positions and, in addition, turn each one 180 degrees.
Staggering and rotating are two things you can do to ensure even baking.