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Sigh. “Why did my cake sink in the middle?” Here in Colorado, high-altitude baking is a special challenge – and having a cake sink in the middle is particularly common. That’s why, when you find a good, basic cake recipe, you usually stick with it through fire and flood. But I like to experiment, and even I can run into trouble with a falling cake.
So why does this happen, and how do you fix it?
Short answer: a sunken cake is almost always too much leavening for the air pressure at your altitude — cut back your baking powder or soda first.
There are a lot of really exhaustive explanations for this, but perhaps it’s easier to think of it this way:
It’s all about air pressure. The earth is surrounded in a thick blanket of air. It’s hard to imagine it weighs anything . . . because it’s AIR, right? But it does, and the further you are down in this blanket, the heavier it is.
If you’re baking at sea level, the air pressure is generally much higher than here at 5,280 feet. This pressure pushes on everything from all directions – the ground, the sides of your house, YOU and your cake batter.
Cake batter is a suspension. The minute you add the “double action” baking powder, the first action is to make some bubbles immediately. The second action is to make a lot more once heat is applied. These bubbles are suspended in your wet flour, eggs, sugar and fat. As the heat continues, the suspension sets permanently and the bubbles are trapped, forming your light, fluffy cake.
But change that air pressure and it all goes to hell. There might not be enough structure (flour or gluten) to support the bubbles. There might not be enough liquid to wet the flour (dry flour doesn’t form gluten at all). You might not have had enough heat at the right time to set the structure. And as the pressure decreases, those bubbles get BIGGER – like a weather balloon rising through the atmosphere. So your problems only get bigger, too.
But unless you’re on Mt. Everest (where water boils at 71° F instead of 212° F and a cake can’t cook at all), there are ways to fix this.
Why Did My Cake Sink in the Middle? And How to Fix It.
When tackling a new basic recipe, try these adjustments, in order:
First – decrease your leavening agent.
The amount of leavening agent you use – baking powder or baking soda – is the single-biggest factor in whether your cake will rise or fall. At high-altitude, too many air bubbles are often the cause of your problems – especially if you notice your cake rising well in the oven, but falling after you take it out. Adjusting the leavening downward is your first step.
Knowing how much leavening to use at your altitude can be found in my post on High Altitude Baking Adjustments. Just use the handy chart.
Second – decrease sugar and increase liquid (do both of these together).
At high-altitude, our flour is usually much drier and “thirstier” than at sea level, so we end up with recipes that have a whacky sugar-to-liquid ratio. Excess sugar weakens the cell structure of your bubbles, so need to cut it down a bit. The flour absorbs more liquid than normal, so you need to add a bit more to compensate. Check the chart at the link above. Usually a tablespoon of milk or water per cup of flour will do the trick. For rich cakes, I add liquid in the form of an extra egg or egg white.
Third – increase flour.
More flour gives your cake more support. I usually start with 1 tablespoon per cup of flour in the existing recipe.
Finally, increase the oven temp by about 25°F.
If your cakes are falling – even at sea level – baking at too low a temperature is a very common culprit. 350°F for a typical cake mix filled with emulsifiers and other suspension aides is probably fine – but from scratch, 375°F is more common. This higher heat allows the cake suspension to set faster, locking in the structure that’s been built already.
Be sure to check your actual oven temp versus relying on your oven thermostat. They are notoriously inaccurate. Mine, for example, is about 10 degrees low at 350°F and even more as it calls for higher temps. (I keep this probe thermometer handy just for this reason.) Plus, it takes a lot longer to reach this temperature than your little oven beeper will lead you to believe.
With this combination, and maybe a bit more tweaking, I can usually get a cake that forms a smooth dome, isn’t dry, and stays set upon cooling.
Why Did My Cake Sink in the Middle? Q&A
Why is a sunken cake so much more common at high altitude specifically?
Lower air pressure means the gas bubbles in your batter expand more than they would at sea level — so a leavening amount that’s perfectly balanced at sea level over-inflates up here, and the structure can’t hold once the cake starts cooling.
Can I save a cake that’s already sunk, or do I have to start over?
Once it’s out of the oven, no — the structure has already set. But it’s not wasted: trim the dip level, fill it with a little extra frosting or a fruit filling, and nobody at the table will know.
Does this apply to boxed mixes too, or only scratch cakes?
Both, though boxed mixes are somewhat more forgiving since they’re loaded with stabilizers and emulsifiers. If a doctored mix is sinking on you, the oven-temperature fix is usually the first place to look before touching the leavening.
How much should I actually cut my baking powder or soda by?
It depends on your exact altitude — I’ve got the specific ratios laid out in my High Altitude Baking Adjustments post, so start there before guessing.
Ready to give it a try? Start with one of my altitude-tested recipes:
- High-Altitude Carrot Cake
- Basic Yellow Cake
- High-Altitude Texas Sheet Cake
- High-Altitude Italian Cream Cake
You know, my mum has issues with the sinking cake every once in a while! When she thinks she got it right, it sinks! I should let her read this ASAP!! Thanks for sharing!!
Hope it helps!
You know, I am reminded of this Japanese anime called Yakitate Japan. It is a show about baking and has lots of information and comedy!
Anyway, my mom is baking a banana cake now!! 😀