cake sags in the middle -- why? in Pastry & Baking Posted September 20, 2006 · Edited September 20, 2006 by JayBassin (log) I made a spice cake last night. You whip eggs and sugar until very light, add melted butter and then alternately add sour cream and the flour/spices/leaveners. Then into the oven.The middle sags. High on the outside part of the cake, low in the middle.What causes this?←You also may have too much leavener. The leavener could react too quickly and puff the center before the structure is set by the heat. How much leavener did you use? You could try cutting down the baking powder. Added note: if the oven temp is too high, you could have the sides cooking too fast. Try using damp kitchen cloths wrapped around the cake pans.