Is it ensure, insure, or assure?
1610s, "small sweet cake consisting largely of ground almonds," from French macaron (16c.), from dialectal Italian maccarone (see macaroni). French meaning said to have been invented 1552 by Rabelais. The -oon ending was conventional in 15c.-17c. English to add emphasis to borrowings of French nouns ending in stressed -on.
cookie or small cake made of sugar, egg white, and almonds, ground or in paste form, or coconut. The origin of the macaroon is uncertain. The name is applied generally to many cookies having the chewy, somewhat airy consistency of the true macaroon.