I imagine everybody knows Leonard Cohen’s song Hallelujah, since, apart from being played regularly on music radio in any one of a hundred versions, it seems to be the mood music of choice for the closing credits of every detective series
Not unique either. Lope de Vega wrote a sonnet that describes the process of writing a sonnet about a sonnet. As a bit of a joke, presumably.
But for real recursion look at songs like ‘The Kentucky Waltz’, ‘The Tennessee Waltz’, ‘The Last Cheater’s Waltz’ (yes, there is a theme developing here), or ‘The Lambeth Walk’ for that matter. The song (B) that the song (A) is about only exists because the song (A) exists, but it (B) didn’t exist to be written about until (A) was written. It couldn’t even exist in the mind of the composer until it had already been written.
Odd, really. But then music, the performance of music, is recursive when it’s done properly. A good musician is constantly responding to the sound that he knows he is about to make.