Riddle me this: a ringtone for Archimedes' heart?

I am a sugary ring with a hole at my heart. Glazed goodness - a lovely work of art. Paired with your coffee, I play the sweetest part. Take a bite and happiness will start.

The answer to this riddle is a piece of cake.

with a shell of gold, I hold riches untold, but once you see me, there’s nothing left for thee. chased for ages, yet never found, not even sure who spoke the lie. for rainbows end up far too high, and no leprechaun’s been seen, outside of Hollywood and meme.

A clockmaker sold every last clock, and had no more materials to make more He got so desperate he sold his own personal clock, he also didn't have a phone or watch If a deadline for an order arrived, you could say he was this in more ways than one