You don't have to give up birthday cakes if you or someone in your family is allergic to eggs or vegan. Just use one of the many potential egg substitutes when making your favorite cake recipe. These substitutes often make your cakes a bit healthier as well as allowing you to avoid using eggs.
Chia or Flax Seeds Mixed With Water
A mix of either chia seeds or ground flaxseeds and water will form a gel that works as a vegan substitute for eggs in baked goods. You could also use the chia seed mixture as a substitute for part of the oil in the recipe, according to a study published in "The Journal of the American Dietetic Association" in June 2010. As long as the chia mixture doesn't make up more than 25 percent of the total egg plus oil in the recipe, it won't greatly affect the taste of the cake.
Commercial Egg Replacer
Another option is to use a commercial egg replacer, which isn't the same as the egg substitutes made of egg whites sold in the grocery store. These dry egg replacement products don't contain any eggs but are instead made with a mix of flour or starches and leavening ingredients. Mix them with water according to the directions on the package and use the resulting mix instead of the eggs called for in your cake recipe.
Applesauce or Other Pureed Fruit
Reduce fat and cholesterol by using applesauce, mashed bananas, pureed prunes or another pureed fruit instead of eggs. The fruit will help keep your cake moist and increase the vitamin content of the cake. Stronger tasting fruits should only be used for cakes with stronger flavors, such as chocolate, rather than white or yellow cakes.
Substituting other ingredients for eggs may change the structure of the cake, making it drier, flatter or more dense. Making other changes in the recipe can fix this problem if it occurs, such as increasing the amount of leavening or the amount of fat, or you can just use a recipe that is formulated not to include eggs.