
Butter the bread slices on one side.

Place 2 slices of bread in a cold, dry frying pan, butter side down, spread a thin layer of mustard on top and place the cheese slices on top of the mustard. Cover the cheese with the remaining 2 slices of bread, butter side up.

Place the frying pan on the fire and fry the sandwiches on both sides until golden brown, during which time the cheese will melt. Do not heat the frying pan too much, fry the sandwiches on low heat.

Place the closed sandwiches on a cutting board and cut each sandwich diagonally. The classic recipe calls for this triangular shape of the finished dish.