The new musical “Cornelia Street,” set in a West Village café with its chef as the protagonist, boasts a number of promising ingredients. The libretto was written by acclaimed playwright Simon Stephens, the winner of Tony and Olivier awards for “The Curious Incident of the Dog in the Night-Time.” The production is being directed by estimable veteran Neil Pepe at his artistic home, Atlantic Theater Company, which has previously nurtured two of this century’s most enchanting new musicals, “Spring Awakening” and “Kimberly Akimbo.”