It is still currently unknown who invented the recipe for mozzarella sticks. However, the oldest documentation acknowledging the existence of "fried cheese sticks" is in "Le Menagier de Paris," which was authored in 1393.
Though most commonly included in menus and products associated with Italian-American cuisine, the actual origin of the first known recipe for mozzarella sticks is Paris, France. Since mozzarella cheese is commonly associated with Italian cuisine and culture, there may be some people who apply the assumption that the snack is Italian in origin. However, historical information dates the food to 15th century France, not Italy.