I would mayo (that sounds so wrong mixing Chinese and English) a single side... mayo side down, slice of cheese and then the other slice of bread with mayo on the top (facing outward). That would crisp up the bread nicely and melt the cheese. The cheese would meld the two pieces of bread together. Now you might get creative by putting something else with the cheese....maybe some ham or salami?

You people need to branch out more. Mayo works on most proteins that you grill...including a steak. I often coat chicken or fish with mayo or a mix of mayo & Dijon mustard. It is a fat. It doesn't make the steak taste like mayo at all. There are some chocolate cake recipes that call for mayo. Look on the Google. This is not new.

My mother makes chicken parmesan by dipping the chicken in mayo before breading it. It's not bad, but it seems to add extra calories without doing anything for flavor.

Indeed, I learned about spreading a thin layer of mayo on fish (on the skin). Works well and skin is easy to remove. I like the idea of combining it with Dijon mustard. I think I first learned this lesson in NYT Food section. BTW, I also learned about Dukes Mayo in NYTimes. (It was a recipe for chicken salad).
Here is quote from NYT "Duke’s mayonnaise, which is free of sweeteners and tangier than most factory versions, is my favorite, but it is available only in stores in the Southern states. (It can also be ordered online.) I like to add crème fraîche or sour cream for chicken salad, which fluffs the texture of the dressing; mayonnaise alone can be greasy.

While only speaking for myself, quite right! It's like Hawaii where it had taken a pandemic and sheer desperation to get me there, and I'm much better for it! It was worth getting kind of ripped off. Had no idea how wonderful and relaxing an island right smack in the middle of the Pacific could be.

For me, this realization is a game changer!

The time between when my kid mayo's the bread, grills the cheese sandwich and consumes it is never more than 15 minutes. - zero food poisoning risk.

Bring the mayo to room temperature, let it sit on potato/tuna/whatever salad in the warm sunshine for 4 hours - odds are good you'll be barfing before dawn.

fresh pesto

bacon

That’s exactly the technique. And as others have mentioned mayo works great on fish. I make a coating with sambal, mayo and tobiko to top salmon - bake at 400 for 12 minutes then broil lightly.

There's an idea. Maybe also pairing it with some sort of soup... Something other than tomato soup...

Yeah, cream of tomato or something. I'd probably take this new mayo grilled pesto cheese extravaganza and dip in the soup a few times.

Pesto soup?

David

I prefer it with a tart apple. Goes so well with the sharp cheddar.

It is a bit of a myth that mayo causes food poisoning. There is enough acid in it (usually lemon juice) and acid slows down the growth of bacteria. Of course, I wouldn't let a sandwich sit in the sun all day but often other ingredients in the dish are the culprits.

I hate skin on fish and sometimes you can't find skinless. I need to try this...you spread the mayo on the skin, then cook and you can just pull the skin off? Wow...I love that.