Luzita - from Logan, UT
There are several possibilities as to why your cakes sink in the middle. First, your cake might not be baked completely through. Make sure you test for doneness before removing from the oven and cooling. Each of our recipes give both a time for baking as well as a test for doneness (often, it’s testing with a toothpick or cake tester).
Another reason might be too much leavening (baking powder or baking soda). Having too much leavening causes the batter to rise quickly, without the cake cell structure forming. When the cell structure isn’t set, the air spaces created by the leavening in the cake collapse, causing the cake to sink.