Baking Soda and Cream of Tartar (Best Option)
1/4 teaspoon baking soda + 1/2 teaspoon cream of tartar per 1 teaspoon baking powderBaking powder is essentially a combination of baking soda (a base) and an acid that react to produce carbon dioxide gas, which leavens the cake. Cream of tartar is an acid that reacts with baking soda to create this gas. Using them together replicates the chemical leavening process.
To ensure success, mix the baking soda and cream of tartar thoroughly with the dry ingredients to avoid uneven rising. Use immediately after mixing as the reaction begins once wet ingredients are combined.
Compared to commercial baking powder, this substitute produces a very similar rise and crumb structure in vanilla cake, preserving the intended lightness and tenderness.