Yeah, it shocks most people when they hear it. But if you think further on it, mayo is essentially oil, egg, and an acid, but mainly oil and egg. Cake mix calls for oil and egg, and so you just substitute a dollop of mayonnaise, and it does a better job of oil and egg.

As far as how much, I have no idea. I’m not a baker. I can cook, but I do not bake.

And for anyone wondering, you do not taste mayo in the cake, that would be terrible.