1. Spread each roll with mustard. Arrange half of pickle, turkey, ham, and cheese slices on each roll; press together gently. Spread outsides of rolls with butter.
2. Place sandwiches in cast-iron skillet over medium-high heat. Put second skillet directly on sandwiches. Press down, and grill 5 to 10 minutes on each side or until cheese is melted and sandwich is flattened and browned.