Observed October 8 in homage to a sandwich of peanut butter and Marshmallow Fluff between two slices of bread, this food holiday honors a treat especially popular among mid 20th century children in New England.

Inspiration for the sandwich began in 1913 when Emma and Amory Curtis of Melrose, Massachusetts invented Snowflake Marshmallow Creme and published a recipe for a peanut butter and marshmallow creme sandwich. The name Flutternutter emerged decades later, in the 1960s, when the advertising agency for Marshmallow Fluff coined it to market its product.