Spread a thin layer of butter on both sides of the bread and set aside. Repeat until all of the sandwiches have been assembled. Have ready a cast iron skillet or a large sauté pan warmed over low heat. Place sandwiches onto the pan. Cook 4 minutes, carefully flip using a spatula and press down on the sandwich to compress it slightly. Cook for an additional 3-4 minutes, until perfectly golden and melty.