I’ve been rewatching Frasier recently (just finished the 7th season) and it is still an absolutely fantastic show. Witty writing, great characters, and very few bad episodes (rare in most comedy series - there are usually a lot of duds as they age).
In any case, one of the episodes I’ve just watched, They’re Playing Our Song, has Frasier composing his own theme tune for his radio show. Rather than being a 10 second jingle, it turns into a 2-minute orchestral track with a voiceover from Niles.
Watch and enjoy: