Eggs are one of the most difficult things to replace in baking. Eggs provide binding and structure to baked goods. Without eggs, your baked items are going to be flatter than they would be otherwise. If you are sensitive to chicken eggs, you might ask your doctor about trying duck eggs. Duck eggs are a terrific substitute for chicken eggs if you can tolerate them, and they are bigger than most chicken eggs – so they naturally replace the “extra-large egg” we recommend in many of our recipes.
If you cannot tolerate duck eggs, the next preferred egg substitute is ground flax seeds mixed with hot water. This creates a flax seed gel that acts as a binder and a source of moisture in the place of eggs. For one extra-large egg, I recommend placing 1 Tbsp. of ground flax seeds in a measuring cup and add hot water until it reaches the ¼ cup line. Whisk the mixture a few times over the course of about 20 minutes to form a gel. Use this gel as you would eggs – you can even beat it with your mixer. If you are using this in a recipe that requires the ingredients to be cold, refrigerate before using.
If your recipe turns out flatter than you want it to be using the flaxseed-egg substitute, you can also a teaspoon of extra baking powder (not baking soda) to improve the rise. However, keep in mind that the resulting item will not be as fluffy as it would be with the use of egg.