Honestly, Idk if it's served all day, but we love to go to Les Halles & get the croissant jambon fromage at the end of the day and take it to our room, put it in the fridge, and heat it up the next day for breakfast. I've never asked them to heat it up in the restaurant because we always get it with the intention of eating it later---but maybe that's something they do or could do?