Comment by derefr

One of those "chef lifehacks" that stuck with me is that you can use mayo in place of butter on the outside of a grilled cheese. Easier to spread, browns perfectly, and turns out to taste exactly the same. (Which is surprising, given that every time I've made a grilled cheese with any kind of oil in place of the butter, it's turned out disgusting. Emulsifying the oil fixes the problem somehow.)