Jean Stapleton, who as dingbat Edith Bunker was a notoriously lousy cook on TV’s “All in the Family,” is playing one of the TV kitchen’s best-known cooks, Julia Child, in a musical monologue, “Bon Appetit!” Stapleton sings her way through Child’s recipes in the one-woman show that played Wednesday at the Kennedy Center in Washington and is due to come West next month, including April 5 in Long Beach and April 9 in Santa Fe, N.M. Child, in an interview with the New York Times, said she’s delighted and flattered by the show: “You can have an awful lot of fun with cooking. It doesn’t have to be serious. . . . I’m a ham anyway.” The monologue was adapted by composer Lee Hoiby from one of Child’s 1961 TV programs.