"Les croissants au beurre sont meilleurs."
Translation:Butter croissants are better.
The term "butter croissant" is not uncommon in the U.S.. I have frequently seen "butter croissant" in bakeries and on menus, as opposed to "chocolate croissants". Though the term "plain croissant" is used slightly more. I've seen butter croissant used both on the East and West coast so I don't think it is a regional thing.