A little history...

A macaron is a sweet confectionery made with egg whites, icing sugar, granulated sugar, almond powder or ground almond, and food coloring.
The macaron is usually filled with a ganache sandwiched between two cookies. Its name is derived from an Italian word "maccarone" or "maccherone". This word is itself derived from ammaccare, meaning crush or beat, used here in reference to the almond paste, which is the principal ingredient. It was during the Renaissance that Catherine de Médicis introduced these delicacies to France on the occasion of her marriage to the Duke d' Orléans, the future king of France.
Before being sandwiched together those cakes were served individually.
At the beginning of the XX century Pierre Desfontaines, grandson of Louis Ernest Ladurée had the idea of sandwiching the two halves together with a filling.