Step 1Heat a cast-iron pan or griddle over low heat. Brush one side of each bread slice with the melted butter.
Step 2Spread half the cheese evenly over the unbuttered sides of two slices of bread, carefully spreading it to the edges. Spread 1 tablespoon of apple butter over each of the unbuttered sides of the two remaining slices, then place them, apple-butter side down, onto the slices spread with cheese.
Step 3With a spatula, place a sandwich into the heated pan and weight it with a second heavy pan or a steak weight. (If your pan is large enough, cook both sandwiches; otherwise, cook them one at a time.) Cook until golden brown, about 3 to 4 minutes. Flip the sandwich and weight it with the pan or steak weight, and cook until golden brown, another 3 to 4 minutes.
Step 4Remove the sandwich to a cutting board and cut it in half or quarters. Serve immediately, with extra apple butter if desired.