One of the main ingredients of the Fluffernutter is Marshmallow Creme. It was invented in the early 20th century by Archibald Query. During World War I, Emma Curtis published a recipe for the "Liberty Sandwich", which consisted of peanut butter and Marshmallow Creme on oat or barley bread. The recipe was published in a promotional booklet sent to Curtis' customers in 1918. It may be the origin of the Fluffernutter sandwich. Earlier labels and booklets by the Curtises suggested combining Snow Flake Marshmallow Creme with peanut butter or eating it on sandwiches with chopped nuts or olives.