David Cook, Katharine McPhee return to American Idol (photo gallery)
American Idol continued to do it right Thursday night, bringing back two of the show’s past stars for guest appearances. David Cook, the Season 7 winner, performed “Heartbeat” while images of past Idols winners were shown on the big screen in the background. The song is from David’s 2015 “Digital Vein” album, which he released…