1. Too much shortening, sugar, or leavening. So be sure you measure accurately! (In this case, it is also possible that the recipe itself was untested and incorrect).
2. Too many egg whites (probably only happens when a cake recipe calls for different amounts of egg white and yolk, for example 1 whole egg and 2 egg whites. Depending on the size of the eggs, your cake can end up with too much egg white).
3. Too slow an oven. Make sure your oven has been preheated for a few minutes, and make sure your oven is accurate. An in-0ven thermometer is a good idea. Also, if your recipe says 350 for regular pans and 325 for dark pans, follow those directions.
4. Probably the most common culprit: the cake is underbaked. There are several tests for checking a cake's doneness and I believe in using them all:
a. Insert a pick into the center of the cake. It should come out clean.
b. Check to see that the cake is beginning to pull away from the sides of the pan.
c. Finally, press it lightly with your finger--it should spring back. If the indentation remains, even if the other tests indicate the cake is done, give it a few more minutes until a light press with your finger springs back.
To my dear friend Melanie, I hope these answers helped!
