I have the giant box of Ener-G egg replacer sitting in my cabinet, but I've found that in most cases a flax egg will do.
1 T flax seed 3 T water Grind the flax in a coffee grinder or mortar & pestle and then mix in the water.
Voila, you have one egg.
cooking.stackexchange.com/users/1699/Dave
As some people pointed out it really depends on what you are trying to make.
(and believe me
it's not easier to replace the girlfriend as someone above suggested, vegan baking is so easy)
You can use the egg replacer that's available at health food stores
(you mix one tbsp with water, following the directions on the box for each egg).
The downside of this is if you are trying to replace several eggs, the powder does give it a weird taste.
For muffins, pancakes, waffles etc.
you can easily replace it using apple sauce and oil.
I've made cookies where the recipe called for mixing oil and maple syrup, i'm sure that's what kept them together instead of egg.
Flax seeds in water also become all sticky like egg and keep things together.
Banana is another great one but your food will taste like banana, so this is great if you don't mind the banana (it works amazingly in brownies).
Silken tofu can be used to make all sort of custard/ mousse desserts.
This site will probably explain it much better than I did above http://www.theppk.com/veganbaking.html
IMO the best cake/ cupcake recipes are from "vegan cupcakes take over the world", they always come out fluffy and tasty, and everyone i made them for loved them and couldn't tell they were vegan, it's a little cookbook i'd invest in if you're planning on baking for her.
Another thing- to replace eggs for breakfast try making scrambled tofu (lots of recipes online),
when it's spiced properly it is SO delicious.
Basically you crumble up firm (not silken) tofu with your hands, add spices (tumeric to make it yellow like scrambled eggs), herbs, nutritional yeast, oil and fry it up.
Mix with diced tomato just before serving, it is super yummy.
cooking.stackexchange.com/users/2362/user2362
In Brownies without egg , Darin Sehnert makes a reference to commercial "Egg replacer".
cooking.stackexchange.com/users/1229/kiamlaluno
In pancakes, I use 2" or so of a banana per egg.
The more banana you use, the more banana-y
it tastes, so no harm done!
If you were to use a little less, it's possible to remove the banana taste completely from the pancakes.
My roommate who HATES banana with a passion tried my pancakes and loved them, claiming she couldn't taste the banana at all.
This substitute is used while making pancakes with your typical Aunt Jemima/generic brand pancake mix, and adding soy milk as well (soy cooks better than almond or rice).
For brownies or cookies, you can use applesauce or maple syrup or more banana, it's really up to you.
Applesauce doesn't add much flavor, thus making them quite similar to real ones.
Maple syrup also works well, but doesn't add to the fluffiness.
If you were to use banana in your brownies, I would recommend blending with a little water, so it's completely smooth and not lumpy.
As ya probably know,
brownie batter from CVS even, can be vegan.
Banana bread is obvious - use more banana! and add walnuts or pecans because of the obvious YUM factor.
I find that using baking powder or soda does NOT work well and would advise against.
If you wanted to make French Toast: I would heat up vanilla soymilk, a little citric fruit juice (orange banana), more banana, seasonings such as cinnamon and vanilla.
Stir in flour to thicken it up a bit, and when its thick enough, soak your bread and cook it up!
cooking.stackexchange.com/users/15626/Jacob Raccuia
There is a commercial egg replacer named Ener-G that you can find at most health-food stores.
Here is a link to the product FAQ: http://www.ener-g.com/Faq/productfaq.aspx .
I wouldn't say it does 100% of the things an egg can do (good luck making a custard with it!), but many vegans seem to find it helpful.
cooking.stackexchange.com/users/1393/Michael Natkin
There was an episode of "Good Eats" where Alton Brown replaced eggs with avocados.
They have similar properties, though I think he fixed the dishes in other ways as well.
cooking.stackexchange.com/users/63/plor
In addition to the many commonly known egg substitutes, there is one less known: aquafaba.
Aquafaba is the resulting liquid from cooking beans and other legumes such as chickpeas in water, and it is quite useful as a substitute for eggs.
The official aquafaba site ( http://www.aquafaba.com ) explains the history, the science, and what has been said about aquafaba.
There are cook books devoted to the use of aquafaba in recipes from lemon cake to Pavlovas and Swiss buttercream: https://www.amazon.com/gp/product/1612437214/ref=crt_ewc_title_oth_6?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
cooking.stackexchange.com/users/61696/Rachelle Greene
I've been using bananas in my brownies since I started living with Vegans (3 years ago) and I've gotten nothing but praise (except for those extremely rare few who truly detest the taste or even smell).
I generally use 1 or 2 (about 8 in / 20cm in length)
but sometimes I'll throw in 3-4 for that extra banana kick.
I also add some water in there (in lieu of milk) and throw some other smaller ingredients into the blender to make a nice liquid which better facilitates mixing (assuming you're doing it by hand).
cooking.stackexchange.com/users/3722/glenneroo
I've been using corn flour as a substitute of eggs in pancakes, with mixed results, but its some option to investigate.
cooking.stackexchange.com/users/2884/miernik
I just found an extensive list of egg substitutes in case you're baking: http://chefinyou.com/egg-substitutes-cooking/
It's a 3 page long table, sorry for not reposting it here.
Not all the options are vegan, but most of them are.
cooking.stackexchange.com/users/36751/Mark
My girlfriend is vegan.  How can I replace eggs in a recipe?   Maybe with banana or soy? How much?  The egg is the key ingredient to keep everything from falling apart.
With what can I replace eggs?
cooking.stackexchange.com
<substitutions><eggs><vegan>
cooking.stackexchange.com/questions/4192
cooking.stackexchange.com/users/1644/Tuomas Hietanen
Ener-G egg replacer is a commercially available option, or you can use a flax egg, silken tofu for custard/mousse desserts, banana in pancakes, apple sauce and oil, avocados or aquafaba. You can buy an egg replacer at most health food stores. Otherwise, try using banana, silken tofu, apple sauce or oil.
You can buy an egg replacer at most health food stores. Substitutes for eggs include banana, silken tofu, apple sauve, oil, avocados and aquafaba.