Adding too much baking powder to a cake recipe can make the cake rise up too much and taste bitter. Moreover, too much baking powder may cause the cake batter to collapse after rising because of the large air bubbles that form inside.
A cake for which too much baking powder was used can have a fragile and coarse crumb after baking. To avoid the effects of adding too much baking powder to a cake recipe, increase the other ingredients to match the amount of baking powder and proceed with the baking process as usual. This will result in a larger cake.