Swapping out eggs in cookies is a snap! Here are just a few reliable ways you can substitute eggs in your next batch of cookies: Flax seed: 3 tablespoons water + 1 tablespoon ground flax seed, soaked in a bowl for 10 minutes = 1 egg Bananas: 1/4 cup mashed banana = 1 egg Applesauce: 1/4 cup applesauce = 1 egg Nut butter: 3 tablespoons nut butter = 1 egg Water + baking powder (my favorite way!): 2 tablespoons water + 2 teaspoons baking powder + 1 teaspoon oil = 1 egg. Keep in mind that substitutions like bananas, applesauce, and nut butter will give your cookies a slightly different flavor. That's why my FAVORITE substitution is water and baking powder. You get a swap that's not only effective, but does not change the flavor of the cookie in any way. In this recipe, since there is plenty of butter (oil), I only use 2 tablespoons of water + 2 teaspoons of baking powder as a stand-in for my egg.