Preheat a Panini press according to the manufacturer's instructions.
Split the roll in half lengthwise and brush lightly with olive oil. Place one of the bread pieces, oiled side down, on work surface and spread the robiola pieces on top. Drizzle very lightly with a few drops of olive oil.
Layer the salami over the cheese, then grind black pepper over to taste. Arrange the arugula leaves over the salami. Cover with the other slice of bread, oiled slice up.
Place the sandwiches on the preheated panini press and cook according to manufacturer's instructions until the sandwich is hot, the bread is golden brown and the cheese is melting.
Serve immediately. Makes one panini.