Baking soda is a key ingredient in creating a light and fluffy butter cake. Its reaction with the acid in buttermilk produces carbon dioxide gas, resulting in a moist and tender cake. It's important to add the baking soda just before baking to maintain the cake's rise. Only a small amount is needed, around half a teaspoon. While some recipes may include both baking soda and baking powder, baking soda is essential when an acid is used.
