To be fair, this is a mistake that started with the Google paper, and everyone else just copies the mistake.

The paper calls them Macaroons as a play on (browser) Cookies with layers (of caveats) - so clearly they meant macarons as well, since a macaroon doesn't have layers. Or at least, that's always been my interpretation of the name. It's possible it was just an arbitrary play on hMAC cookies and not the layers?