Here are the top things you will be searching for to save yours keep a cake from falling apart the next time you bake:
Old Baking Powder
Baking Powder can only compensate for a small proportion of all of the cake ingredients, but it will spoil the entire thing if you are not careful!
Do not you know if theirs is still good? Take 5 seconds to test it before you continue cooking by adding a tablespoon of baking powder in around 1/2 cup of hot water. If it is still fine, it will start to bubble quickly. If this happens, it is time to go to the supermarket.
Too Much Leavening
The amount of air that is produced in the cake will be greater than the structure of support, and the entire thing will come crashing down.
Always apply extra baking powder or other leaflets to the flour or cake mixtures, and please make sure to read the formula thoroughly and calculate carefully to keep a cake from falling after baking.
When in question, note that the typical ratio of baking powder to flour is one to one and half teaspoons per cup of AP flour; and if you see a formula that asks for anything much above that, it is definitely incorrect.
This is possibly one of the most common causes for cakes to sink. I am not sure what it is, but we all seem to have a strong propensity to overbeat the cake until it is soft and fluffy.
But bashing the battery with too much air until the dry and wet components are mixed would just allow the battery to sink.
Go ahead and put the air in while you are creaming milk, sugar, and eggs, but as soon as you add the flour mixture, note that it is ALL in the light side.
Thread the dry ingredients into the wet until they are just mixed, then gently separate and dump into your cake pans. If you add something at the edge, start to work the addition through the batter as softly as possible in a fluid folding motion.
Even, should not be afraid to look inside the oven for at least the first 80 percent of the estimated baking time.
Note that any time you open the door to the oven, the temperature inside will drop as much as 10 degrees. Such minor temperature variations can have an effect on even growing cakes.