Self Raising Flour Plus Baking Powder

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Self-raising flour contains baking powder in a proportion that is perfect for most sponge cakes, such as a Victoria sponge, and for cupcakes. Some recipes may ask for a little addicional baking powder to be added, particularly if the cake is made with an all-in-one method as omitting the creaming stage in the cake making means less air is incorpoated into the batter during the mixing stage. Sometimes also a small amout of bicarbonate of soda (baking soda) is added if the ingredients include cocoa powder, yogurt or buttermilk.

However you should only ever add extra baking powder or bicarbonate of soda (leavening) if the recipe asks for it. Adding too much extra leavening in the hope of making something rise more can actually have the opposite effect. If there is too much leavening in the cake then as the cake bakes the it rises up too much and then falls back very quickly as the cake cools, leaving a sunken cake with a very wrinkled surface. In addition, too much baking powder or bicarbonate of soda can give an unpleasant, slightly bitter taste.