Use cheddar of any type, Edam, Gouda, Colby, “Swiss,” or Monterey Jack. Cut into cubes of less than in inch, and arrange on an ungreased baking sheet.
Here’s where I tell you not to crowd the cheese bits, but it seems no matter how meticulous I am, I usually end up having to break them apart. Place in the upper rack of a low (250) oven until it’s thin, crisp, bubbly, and greasy. Cool completely before removing with a thin spatula to drain.
You shouldn’t have to salt these, but some people like paprika or cayenne. I don’t. Eat immediately; they’re too fragile to keep.