To keep the center of a sponge cake from sinking, beat the eggs thoroughly, fold the batter gently, preheat the oven, and keep the door closed until the cake is done. Sponge cakes are sensitive to sudden temperature changes. Their centers can sink if the air trapped in the batter collapses before the cake structure has set. Overmixing or underbeating the eggs can also reduce the cake's volume. Careful mixing and a steady oven temperature help prevent this problem.
How to bake a sponge cake so the center stays raised
• Beat the eggs and sugar until the mixture becomes noticeably lighter in color and increases in volume.
• Sift the flour into the egg mixture and gently fold it in from the bottom up.
• Fully preheat the oven to the recipe's specified temperature, usually 170–180°C / 340–355°F.
• Place the pan on the middle rack for even heat.
• Keep the oven door closed until the cake is nearly done; do not open it during the first 25–30 minutes.
• Check doneness by inserting a toothpick into the center; it should come out clean.
Common mistakes
Not beating the eggs enough can prevent the cake from gaining the needed volume and lightness. Mixing the flour too firmly or for too long can knock air out of the batter. Putting the cake into an oven that has not fully preheated can lead to uneven baking, and opening the oven door too early can cause a sudden temperature drop that makes the center collapse.
Why should you keep the oven door closed?
As the cake rises, its air and steam bubbles form a fragile structure. Opening the door early lets cooler air in and can make that structure collapse. The early part of baking is especially important, so keep the door closed.
Can baking powder make a cake sink?
Too much baking powder can make a cake rise quickly and then sink because its structure may not set firmly enough to support the expansion. Too little leavening can keep the cake from rising. Measure baking powder according to the recipe.
Thoroughly beaten eggs, gentle folding, a fully preheated oven, and keeping the oven door closed early in baking all help a sponge cake rise evenly. Bake patiently at the recipe's temperature to preserve its light, fluffy texture.