It is frustrating when you spend time preparing a cake mix, only to see your cake sag in the middle when you remove it from the oven. When a cake falls in the middle, it spoils the look and the taste of the cake. The fallen part is often compacted and damp, leaving you with a soggy taste in your mouth. You can attempt to hide the dip in the middle when you put frosting on the cake, but often the final results are poor. There are some good reasons why cakes fall when baking.
Check the temperature specified in the recipe. If the oven temperature is too low, the cake will not rise properly. Give the oven 20 minutes to heat up to ensure that it is up to temperature before you put in the cake. Use an oven thermometer, purchased from a hardware store, to check the temperature of your oven. The dial on the oven may be inaccurate to the temperature in the oven. If the oven dial and the thermometer do not match, then the oven requires calibrating. An oven running at an incorrect temperature can cause a cake to cook too quickly or too slowly, preventing the cake form rising properly, or falling when it is removed from the oven.
Measurements of Ingredients
Read the recipe carefully to ensure that your measurements are correct. If the cake mix is too runny or too solid, then the cake will not rise correctly and will fall in the middle. Check how much milk or water should be added. Too much or too little sugar, baking soda or flour can also cause sagging. When using a measuring cup or measuring spoon, ensure that you level off the top of the flour or other ingredients with a knife — doing so ensures an exact measurement.
Adhere to the baking time set in the recipe. If you take the cake out of the oven too soon, before it has properly risen and set, the center of the cake will fall back down. Likewise, if after the cooking time is complete, the cake does not appear thoroughly cooked, then give it a few minutes longer in the oven. To test if the cake is ready, insert a skewer or other thin object, vertically down into the center of the cake. Pull it out and examine the residue on the skewer. There should be a few crumbs on the skewer and nothing else. If there is wet cake mix on the skewer, then the cake is not ready and you must put it back in the oven before the center has a chance to fall.
Opening the Oven Door
Avoid opening the door of the oven while the cake is baking. The hot air escapes and the temperature of the oven reduces. This change in temperature prevents the cake from rising properly. Opening the door repeatedly prevents the oven from maintaining its temperature throughout the cooking process.
Overworking the Cake Mix
Mix the cake according to the instructions. If the cake mix is beaten too much, it will contain excessive air. Likewise, if the ingredients are not properly mixed together then there will be uneven patches throughout the mixture and very little air. These imbalances can prevent the cake from rising properly.
References and ResourcesZomba: Tell Me Why: Why Did My Cake Fall in the Middle?
Science of Cooking: "What makes cakes fall?"
Chef Rick's Southern Cooking: Why Cakes Fall