In French, the word she is said to have used is brioche. It's a fancy bread made from white flour, eggs, and huge amounts of butter. It's also very labor intensive. All of those things would put it well out of reach for those starving in France at the time. They were already eating the "lowly" bread.

This is a very short reply, so I'll add that there's a similar story going around where the actual meaning of the "let them eat..." phrase is what you said. Joseph Foullon was the minister of finance around the time of the storming of the Bastille. He was supposed to have said "If those rascals have no bread, then let them eat hay". On July 22, 1789, he was lynched by a mob. After he was hanged, they cut off his head and paraded it around - with the mouth stuffed full of hay.

Firstly, it's an apocryphal story; she didn't really say that, it's kind of a legend that's sprung up around her.

Secondly, in the story, she does mean cake. The story goes that while Marie Antoinette was living the high life in Versailles, the peasants were starving and struggling to survive. When someone told her they had no bread, she said "So let them eat cake!" -- the point being that she was so oblivious and pampered and sheltered that she couldn't even understand the idea of starvation, and assumed that the starving peasant workers and farmers could just go grab themselves a nice cake if they had run out of bread. The dish she is referring to is a sweet pastry made with lots of butter and eggs, often served with chocolate, making it obviously more luxurious than plain bread.

hi! not discouraging other responses, but you'll find a brief response regarding that line in this post

Was Marie Antoinette as dumb and selfish as history paints her?