Working in batches if needed, heat skillet over medium-high heat. Brush with butter and place bread in a single layer. Cook until golden brown on one side, then remove from skillet.

Brush a little additional butter on skillet and sprinkle the bottom of the skillet with a layer of Parmesan cheese. When the edges have begun to brown, press the bread into the cheese, toasted side up. Continue to heat for a minute or two longer until the cheese is golden brown.

Remove skillet from heat, loosen the edges of the cheese and turn over onto a plate, platter or cutting board. Let cool until easy to handle then cut between the toasts to separate them.