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 (often cream of tartar). Using baking soda with cream of tartar replicates this balance, producing carbon dioxide gas during baking that leavens the dough. This reaction is immediate upon mixing and heat activation, ensuring the cookies rise properly.
For best results, mix the baking soda and cream of tartar thoroughly into the dry ingredients to ensure even leavening. Avoid overmixing the dough afterward to prevent tough cookies.
Compared to commercial baking powder, this substitute yields very similar texture and rise, preserving the classic tender and slightly crisp sugar cookie characteristics.