Kayla - from Akron, IA
If you haven't checked the temperature of your oven lately, buy an inexpensive oven thermometer from the grocery store and see if it is accurate. Some ovens have a difficult time maintaining a constant heat, so it is possible that the oven got hotter than it should have. Ovens can also have "hot spots," parts of the oven where the heat is higher. Next time you bake a cake, set a time for half way through the baking time and rotate the pan to ensure even baking. Finally, when doing a side-by-side cake, make sure that the chocolate and white cake mixes have the same baking times. If not, you can always bake the cakes separately, put them side-by-side, and ice them together.