I just made these for lunch today, and they were scarfed down by 3 generations. The possibilities for sandwich fillings are endless, but the bread treatment makes all the difference. I had a sandwich similar to this at First Watch yesterday and wanted to see if it was do-able at home.
I used sliced ciabatta bread (Kroger Private Selection) and muenster cheese (Finlandia, from Costco). After buttering the bread slices, I sprinkled the butter with shredded Parmigiano Reggiano cheese and pressed the cheese into the butter. I made the sandwiches on a griddle, medium-heat, and the Parm/Regg got all crusty while they grilled. As my "nephew" Andy Taylor would say, they were "extry-good!" I can't wait to try these with some fresh mozzarella, basil, sun-dried tomatoes as filling.