Wash and cut your potatoes into 1-inch size chunks. Put the potatoes on a baking sheet and add the rosemary, salt, pepper and olive oil. Toss together until well coated then spread into a single layer.
Roast the potatoes for 45 minutes turning them around with a spatula halfway through, so they brown all the way around.
Once roasted, drizzle the potatoes with the truffle oil and truffle salt (if using). Then give the potatoes a gentle toss to get the truffle oil all over. Place in serving dish and top with shaved Parmesan and parsley. Serve!