Melt 1 tablespoon butter in a large cast iron skillet or griddle over medium-low heat. Sprinkle a pinch of kosher salt.

Prepare sandwiches on a nearby surface by laying one piece of bread down, topping with cheese and optional additions and other slice of bread.

Place 2 sandwiches in pan, careful not to overcrowd and cook until golden brown, about 5 minutes. Flip over, add another 1 tablespoon oil and cook another 5 minutes.

Serve with tomato soup.