A 'proper' cheesesteak uses Cheez Whiz. Provolone may make it a much better sammitch (and it does for many), but Cheez Whiz is needed for authenticity. Similarly, if you don't use that Amoroso bread, it's not authentic.
The original poster requested "authentic". If he meant 'best tasting', this thread is most helpful.
Similar to the oft-debated Chicago style pizza -- cornmeal in the dough or not? NO, if you want authentic. YES, if you want something that many believe improves on the original.
Homemade mortarless bread oven.
KCBS member ... primarily so I can get into Restaurant Depot.