At New York’s Café Carlyle in May, the “punk-vaudeville” band Nancy and Beth thought broadly. In addition to touching on jazz, country, soul, and gospel, the proceedings included choreographed dance moves and sidesplitting between-tune chitchat. But the scope of the performance was nearly outmatched by the star power onstage: Nancy and Beth—the group formed in 2012 and released a self-titled album last year—is fronted by the actresses Megan Mullally, 59, and Stephanie Hunt, 29, the former best known for her work as Karen Walker on Will & Grace. And as a bonus, the ensemble was introduced by Mullally’s husband, the actor Nick Offerman, a.k.a. Parks and Recreation’s Ron Swanson. Before one of their Carlyle sets, Mullally, Hunt, and Petra Haden—a daughter of jazz bass great Charlie Haden, Petra sings and…