The question of who invented PB and J sandwiches—or at least who wrote it down as a recipe—can be answered with the name of Julia Davis Chandler. In 1901, she was the first to name this type of sandwich on record in the Boston Cooking School Magazine of Culinary Science & Domestic Economics, recommending currant or crab-apple jelly to make for a very “original” sandwich.
While at the time the PB and J was not a food of the masses yet, Joseph Rosefield turned peanut oil into a saturated fat in 1922. This landmark alteration prevented peanut butter from going rancid so soon and from sticking to the roof of your mouth. He called this new brand of peanut butter “Skippy.”