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 baking soda combined with an acid (usually cream of tartar) and a moisture absorber. Using baking soda with cream of tartar replicates this balance, producing carbon dioxide gas when heated, which aerates the cookie dough.
For best results, mix these two powders thoroughly into the dry ingredients to ensure even leavening. Avoid adding extra acidic ingredients as this can cause over-leavening or off tastes.
Compared to commercial baking powder, this substitute provides a very similar rise and texture, preserving the classic chewy yet tender crumb expected in chocolate chip cookies.