Grate your parm, place in on a silpat lined baking sheet, bake at 400 F (200 C) for 5 minutes. Be careful because these burn easily. You can shape them right out of the oven when they are still pliable or use a cutter to get a super clean shape.
I've found that if you use the inner part of the parmesan as opposed to the harder stuff near the rind you get much better results. I think it has something to do with the moisture in the cheese separating from the fat.