53.85Apply it to “Happy Birthday”

Make it absurdly economical.

Phrase 1: melody mostly untouched.

Phrase 2: reduce melody to a tiny recognizable fragment.

Phrase 3: use only two or three notes from that fragment as blues riff material.

Phrase 4: bring the full melody back.

Now the transformation goes:

tune → abstraction → riff → tune.

This is genuine thematic development.