Shaffer wrote and performs the theme song and bridging music on Letterman's current Netflix series "My Next Guest Needs No Introduction with David Letterman" which premiered in 2018. After Netflix announced publicly that it had given the series an order, Shaffer received a phone call from Letterman asking him to work on the show. Soon after, Shaffer began to receive cuts of episodes from the first season and he started to put music in afterwards where the director thought it was needed. In developing the sound of the show's music, Shaffer initially looked to Letterman for guidance. Finding none, he remembered his and Letterman’s shared love for the sort of music produced at the Muscle Shoals Sound Studio in Sheffield, Alabama, describing it as "the honesty you hear, the southern soul feeling". The score initially included drums, but the show's producers and director thought that the music should "feel like it's Dave's old friend Paul playing", so it was ultimately stripped down to solely include piano and organ.