A cake usually sinks in the middle when the structure in the center never sets firmly enough to support its own weight, then collapses as it cools. The most common reasons are underbaking, oven temperature issues, or problems with mixing and leavening.
Most common causes
- Underbaked center: If the cake is taken out too early, the outside can look done while the middle is still wet, so it caves in as it cools.
- Wrong oven temperature: An oven that runs too hot can brown the edges quickly while leaving the middle undercooked; too cool and the cake may never rise and set properly.
- Too much or too little leavening: Extra baking powder or soda can make the cake puff up fast and then collapse, while weak/expired leavening can make it barely rise and sink.
- Overmixing or undermixing batter: Overmixing can trap excess air and overdevelop gluten so the cake rises then falls; undermixing can leave weak structure and uneven baking.
- Opening the oven door early: A sudden drop in temperature before the center has set can cause the middle to fall.
- Incorrect ingredient ratios or pan size: Too much liquid or fat, not enough flour or eggs, or too much batter in one pan can all lead to a weak center that sinks.
How to prevent it next time
- Bake until fully done: Use a toothpick or skewer in the center; it should come out clean or with a few crumbs, not wet batter, before you remove the cake.
- Check oven accuracy: Use an oven thermometer and bake on the center rack at the recipe temperature.
- Measure and mix carefully: Weigh or level ingredients, use fresh baking powder/soda, and mix only until combined.
- Avoid early peeking: Do not open the door in the first 20–30 minutes unless absolutely necessary.
- Use the right pan and fill level: Match the recipe’s pan size and avoid overfilling; typically, fill cake pans about halfway to two‑thirds full.
If you describe your recipe, pan size, and what the inside of the sunken part looked like (wet, gummy, or just low), it is possible to narrow down which of these is most likely in your case.
