Local favorite Portillo's specializes in classic Chicago-style hot dogs and an otherworldly chocolate cake that keeps fans coming back for more. They know what they're doing when it comes to hot dogs: the first Portillo's hot dog stand opened in 1963. They also know what they're doing when it comes to chocolate cake: they put it in milkshakes. That's right -- their chocolate cake shake comes blended with generous chunks of the lauded dessert. It's truly a masterpiece.