Preheat: Panini grill to high setting or skillet to moderate heat
Lightly butter one side of each slice of bread (or brush with olive oil). Place half of the bread slices buttered side down, and layer with half of the cheese, prosciutto and the remaining cheese, folding back the edges of the cheese if they extend past the edges of the bread. Place the top slice of bread over the cheese, buttered side up.
Grill the sandwiches in a moderately hot skillet or in a Panini grill for 4-5 minutes until the bread is golden brown and the cheese has melted. If working in a skillet, turn sandwiches over halfway through grilling. Cut each in half on the diagonal and serve.
Serves: 4