A long time ago I saw a cartoon that was probably made in the 1950's
or 1960's, in the USA, and was a 'one-off', featuring characters that
only appeared in that particular cartoon.

The plot: a composer of jazz music is stuck as to what to write, when
he hears an alley-cat yowling outside his window. He writes a piece
based on the notes the cat 'sings', this breaks his creative block,
and he becomes very successful. He also gives the cat a home.

For some reason, he eventually chucks the cat out, but without his
muse ('mews'?) he loses his creativity. He then searches for the cat
and takes it in again.

It turns out the cat's a she, and the last scene is of the composer
playing his music on television, and the cat and her kittens gathered
round the TV watching the show.

It was a beautifully made cartoon - can anyone tell me the title?
Thanks.