The Philly cheesesteak began with a South Philly hot dog stand operated by brothers Pat and Harry Olivier in the 1930s, and adding cheese to the soft roll full of beef and onions only became popular in the 1950s. This beloved sandwich has indeed gone through an evolution, but today, it's still only acceptable to use three kinds of cheese.

Never ask for Swiss, cheddar, mozzarella, or parmesan cheese on your cheesesteak at a Philly steak joint, unless you want to get the locals heated. Allrecipes' Nicole McLaughlin explains that “There are only three types of cheese you should use: provolone, cheese wiz, or American cheese. They're all authentic so it's a matter of taste.”

Frank Oliveri, Pat’s nephew, says, “The first cheese was a provolone cheese. We had a manager named Joe Lorenza, or Cocky Joe […] he was the first person to put cheese on the sandwich.” Olivieri adds, “Pat never wanted cheese at his original shop because he tried to keep sort of kosher for all his Jewish friends.”