This post by our friend Kristen at Food Renegade, describes the process of making chia seed eggs in more detail if you are curious. (wellness-media.com)
I haven't tried this recipe with a flax or chia seed egg so I can't say for sure if it would hold together or not. (everydayfull.com)
You could try chia seed egg, or just decrease the number of eggs — 2 should work, but you'll probably need to increase the amount of almond milk a bit They might be a bit gooey - er, but that's always a good thing with brownies (theloopywhisk.com)