Clowns want to play Hamlet, tragedians want to do slapstick, and musical-theater divas want to sing everybody else’s songs. Since those are all traditionally bad ideas, Barbara Cook, in the last case, must be the exception who proves the rule. Here is a diva who’s shaped her own special brand of show, so she could annex songs openly instead of filching them behind her colleagues’ backs. That openness is the hallmark of everything Cook does, from the silvery open A at the top of her range to the open, carefree gesture with which she signals accompanist Wally Harper to start over because she’s just blown a tricky lyric.
Cook’s assemblage does include tidbits from her own celebrated Broadway career, but most of the lineup comes from shows she never appeared in and roles she never played. Not to worry: Her selection of what she can do is unerring, and almost every number is a revelation. “The Gentleman Is a Dope” and “What’ll I Do?” have a mature, bluesy pathos; when she dives into “Mr. Snow,” the years fall away and she’s 19 again. After such bliss, she can frizz any lyric she wants.