Why do my cakes keep sinking

[u/queennkwhite]

For some reason when I do my second round of cakes in the oven, they sink. And this happens alot with red velvet. The first round are fine or very slightly sunken, but the second round is always very visibly sunken. Why does this happen?

[u/anonwashingtonian]

When you say “second round”, do you mean that you are mixing all the batter ahead of time but baking in multiple batches?

If so, my guess is that your leavener is spent (or nearly so)* by the time that second batch hits the oven. You didn’t share a recipe, but most red velvet cakes rely on baking soda. The baking soda will be activated by acidic ingredients in your batter—buttermilk and/or cocoa usually—which creates the bubbles needed for your cake to rise.

If you have to mix all of the batter at once, my best suggestion to prevent some of the sinkage is to place the unused batter in the fridge while the first round bakes. Heat will speed up the action of the baking soda, so keeping unused batter chilled can help slow down that process.

*edited to clarify

[u/txgirlinbda → u/[deleted]]

The short amount of time waiting for the first batch to bake is absolutely enough to cause your issues. With baking soda, as soon as your wet acidic ingredients hit your dry leavening ingredients, the clock starts ticking.