These simple and elegant sandwiches are served in wine and coffee bars throughout Italy. The crusts are removed, then the sandwiches are cut on the diagonal into triangles. In addition to thinly sliced meat, other popular tramezzini fillings include canned tuna and capers, and hard-cooked eggs and mayonnaise. For an extra-special touch, butter the outside of the sandwiches and grill them in a sandwich press or on a grill pan.
Lightly butter both sides of bread slices. Onto 4 slices of bread, layer prosciutto, a few leaves of arugula, and some fennel. Top with remaining bread slices. Grill in a sandwich press or grill pan until grill marks appear, about 30 seconds on each side. Cut sandwiches on the diagonal, creating two triangles.