Heat a skillet over medium heat. Spread butter on one side of all eight slices of bread. Spread Dijon mustard on the opposite side of four slices of bread. Top the mustard-coated bread slices with a folded slice of Emmentaler. Top the cheese with slices of pickle and set the tops in place with the buttered side facing up.
Place the sandwiches in hot skillet and cook for 3-4 minutes on each side, toasting and crisping the bread. Cut the sandwiches corner-to-corner and serve.