There isn't really that much traditional food in Monaco. Monaco is mostly surrounded by France and is heavily influenced by French culture; Monaco also lies near the Italy and has been mildly influenced by Italian culture as well. So traditional food in Monaco would be French or Italian cuisine.
Monaco is aplace as famed for its restaurants as its casinos, so there is lots of excellent and much loved food. When I was last there my favorites were Stocafi and Barbaguian, basically a stewed cod fillet in sauce and a tasty pasty.