Can I use American cheese sliced in the deli to replace the individually wrapped cheese slices? Or is it too big a difference?

I would also totally replace the American cheese with any other real cheese: parm, cheddar, fontina, and gruyere are all classics. But the options of real cheeses are endless, and if you speak with someone at a cheese counter, he or she will help you out.

I would urge you to try it with the sliced American cheese. It melts like nothing else. It also balances the sharpness of the cheddar and the nuttiness of the Parmigiano Reggiano quite nicely.

Do keep in mind that whether it's deli cheese or cheese slices, it isn't really cheese at all. It is a cheese-like food. I would recommend, no I would urge you, to try the recipe with real cheese, a full-flavored Vermont cheddar for instance, and see what a huge difference it makes.

Yes, you can use deli cheese, too.