Some ingredients are easy to leave out when you're baking. Eggs aren't one of those. Making a cake without eggs is a bit of a challenge, even for experienced bakers, but there are plenty of substitutes you can use. Which you choose comes down to your reason for going eggless. If the cake's half-mixed and you've just discovered you're out of eggs, you can work with whatever's in your pantry. If you're going vegan, or are keeping an allergy friendly kitchen, you can think long-term and keep some helpful, less-common ingredients on hand.
It's easy to mistake eggs for a simple ingredient, because they're so common and familiar. That's a mistake, because eggs are the baker's equivalent of a Swiss army knife. They actually have several jobs in a cake, and it's almost impossible for one substitute to do everything eggs do. They add moisture because they contain a lot of water, and the proteins in egg whites help give the cake its structure as it sets. When you beat the eggs into the batter, and especially if you whip the whites, those tiny air bubbles expand in the oven and help the cake rise. The yolks are fatty and make your cake richer, but more importantly, they're also full of lecithin and other emulsifiers, which help the other ingredients in your cake mix together in a smooth batter. You don't have to be a food science geek to figure out that replacing all of those different functions will be a big job.
Use Commercial Egg Replacers
The obvious first choice for replacing eggs is, well...egg replacers. There are a couple of different kinds, so which to choose is all about your reason for avoiding eggs. If you just don't use them for anything but baking, a liquid egg substitute is fine. You can keep it on hand for those times when you feel like baking, and use it as directed on the packaging. The downside to these is that they do contain egg, so they're no good for vegans or anyone with egg allergies. For truly eggless baking, you need the vegan-friendly, powdered egg replacer. It's made from a mixture of ingredients, including some leaveners to help the cake rise and starches that mimic the egg's ability to give structure.
Try Gums and Gels
You can use a variety of gums and gels to give your cake some structure. If you keep flax seed in your pantry for its omega-3 fatty acids, you're all set: It makes a great egg replacer. Stir a tablespoon of ground flax into two tablespoons of warm water and let it sit for a minute for one egg's worth of substitute. Another option is to dissolve 2 teaspoons of plain gelatin in a cup of boiling water, and then when it cools, use 3 1/2 tablespoons of the gelatin mixture per egg. If you keep an allergy-friendly kitchen, and have xanthan gum on hand in your pantry, that's a good egg replacer, as well. You'll need one teaspoon per egg as a substitute, and it's best mixed into the oil or fat your recipe calls for. Xanthan gum acts as an emulsifier as well as providing structure, so it's especially useful if you expect to do eggless baking on a regular basis.
Use Fruit Purees and Dairy Products
Have you seen recipes going around on social media that call for just a box of cake mix and a can of pumpkin puree? If so, you're already familiar with another potential substitute. Fruit purees, including applesauce, mashed banana and canned pumpkin – yes, pumpkin's technically a fruit – can be used in some cakes to provide the moisture that would normally come from eggs. Another option is thick dairy products like sour cream or Greek-style yogurt. Yogurt's obviously the healthier option, and it has the advantage of supplying the protein you lose out on when you drop the eggs. Silken tofu works much the same way, if you're vegan or lactose-intolerant, and there are also non-dairy yogurts you can choose.
Get a Rise
Most substitutions don't help replace the rise you get from eggs, so most of the time plan to add a little extra baking powder or baking soda to compensate. Baking soda works with acidic add-ins like applesauce or yogurt; otherwise, you should use baking powder instead.
Another possible replacement is truly weird: It's the starchy water that comes from a can of chickpeas. This thick liquid whips up just like egg whites, meaning you can use it the same way in cakes. You'll need about three tablespoons of the unwhipped liquid – it's called aquafaba, Latin for "bean water" – to replace a whole egg, or two to replace an egg white. Fold the foam gently into your batter, just as you would real egg whites.
Manage Your Expectations
It's important to have realistic expectations for your finished cake. Kids with Food Allergies, an organization for allergic children and their caregivers, says pretty bluntly that the more egg-centric your recipe is, the less satisfactory the end result is going to be: Substitutes work best in recipes with one or two eggs, not a half-dozen. If you're making a one-off eggless cake because you just don't have eggs, that's not necessarily a deal breaker. Your cake will be denser and chewier, instead of light and fluffy, but it's still sweet and it'll still taste good.
If you're permanently eggless because of an allergy or because you're a vegan, you can start with well-proven recipes designed from the ground up to work without eggs. Once you've mastered those, experiment more with new recipes of your own, or find ways to adapt family favorites. Usually the best path is to combine multiple options – perhaps a gel, some aquafaba and extra baking powder – to replace as many of the eggs' functions as possible.